diff --git a/homeassistant/components/fritz/const.py b/homeassistant/components/fritz/const.py
index 032efb3f4ae9..5050907c1d87 100644
--- a/homeassistant/components/fritz/const.py
+++ b/homeassistant/components/fritz/const.py
@@ -66,8 +66,6 @@ SWITCH_TYPE_WIFINETWORK = "WiFiNetwork"
 
 BUTTON_TYPE_WOL = "WakeOnLan"
 
-UPTIME_DEVIATION = 5
-
 FRITZ_EXCEPTIONS = (
     ConnectionError,
     FritzActionError,
diff --git a/homeassistant/components/fritz/sensor.py b/homeassistant/components/fritz/sensor.py
index 41fa3fca056d..4bd54a751d50 100644
--- a/homeassistant/components/fritz/sensor.py
+++ b/homeassistant/components/fritz/sensor.py
@@ -28,7 +28,7 @@ from homeassistant.helpers.entity_platform import AddConfigEntryEntitiesCallback
 from homeassistant.helpers.typing import StateType
 from homeassistant.util.dt import utcnow
 
-from .const import DSL_CONNECTION, UPTIME_DEVIATION
+from .const import DSL_CONNECTION
 from .coordinator import FritzConfigEntry
 from .entity import FritzBoxBaseCoordinatorEntity, FritzEntityDescription
 from .models import ConnectionInfo
@@ -39,31 +39,18 @@ _LOGGER = logging.getLogger(__name__)
 PARALLEL_UPDATES = 0
 
 
-def _uptime_calculation(seconds_uptime: float, last_value: datetime | None) -> datetime:
-    """Calculate uptime with deviation."""
-    delta_uptime = utcnow() - timedelta(seconds=seconds_uptime)
-
-    if (
-        not last_value
-        or abs((delta_uptime - last_value).total_seconds()) > UPTIME_DEVIATION
-    ):
-        return delta_uptime
-
-    return last_value
-
-
 def _retrieve_device_uptime_state(
-    status: FritzStatus, last_value: datetime
+    status: FritzStatus, last_value: datetime | None
 ) -> datetime:
     """Return uptime from device."""
-    return _uptime_calculation(status.device_uptime, last_value)
+    return utcnow() - timedelta(seconds=status.device_uptime)
 
 
 def _retrieve_connection_uptime_state(
     status: FritzStatus, last_value: datetime | None
 ) -> datetime:
     """Return uptime from connection."""
-    return _uptime_calculation(status.connection_uptime, last_value)
+    return utcnow() - timedelta(seconds=status.connection_uptime)
 
 
 def _retrieve_external_ip_state(status: FritzStatus, last_value: str) -> str:
@@ -200,7 +187,7 @@ CONNECTION_SENSOR_TYPES: tuple[FritzConnectionSensorEntityDescription, ...] = (
     FritzConnectionSensorEntityDescription(
         key="connection_uptime",
         translation_key="connection_uptime",
-        device_class=SensorDeviceClass.TIMESTAMP,
+        device_class=SensorDeviceClass.UPTIME,
         entity_category=EntityCategory.DIAGNOSTIC,
         value_fn=_retrieve_connection_uptime_state,
     ),
@@ -308,7 +295,7 @@ DEVICE_SENSOR_TYPES: tuple[FritzDeviceSensorEntityDescription, ...] = (
     FritzDeviceSensorEntityDescription(
         key="device_uptime",
         translation_key="device_uptime",
-        device_class=SensorDeviceClass.TIMESTAMP,
+        device_class=SensorDeviceClass.UPTIME,
         entity_category=EntityCategory.DIAGNOSTIC,
         value_fn=_retrieve_device_uptime_state,
     ),
diff --git a/homeassistant/components/homeassistant/triggers/time.py b/homeassistant/components/homeassistant/triggers/time.py
index 27c63742f7b8..0fc5618c122f 100644
--- a/homeassistant/components/homeassistant/triggers/time.py
+++ b/homeassistant/components/homeassistant/triggers/time.py
@@ -225,7 +225,7 @@ async def async_attach_trigger(  # noqa: C901
         elif (
             new_state.domain == "sensor"
             and new_state.attributes.get(ATTR_DEVICE_CLASS)
-            == sensor.SensorDeviceClass.TIMESTAMP
+            in (sensor.SensorDeviceClass.TIMESTAMP, sensor.SensorDeviceClass.UPTIME)
             and new_state.state not in (STATE_UNAVAILABLE, STATE_UNKNOWN)
         ):
             trigger_dt = dt_util.parse_datetime(new_state.state)
diff --git a/homeassistant/components/sensor/__init__.py b/homeassistant/components/sensor/__init__.py
index 3148b0d13c2a..73ea6db50365 100644
--- a/homeassistant/components/sensor/__init__.py
+++ b/homeassistant/components/sensor/__init__.py
@@ -3,7 +3,7 @@
 from __future__ import annotations
 
 import asyncio
-from collections.abc import Mapping
+from collections.abc import Callable, Mapping
 from contextlib import suppress
 from dataclasses import dataclass
 from datetime import UTC, date, datetime, timedelta
@@ -32,6 +32,7 @@ from homeassistant.helpers.typing import UNDEFINED, ConfigType, StateType, Undef
 from homeassistant.util import dt as dt_util
 from homeassistant.util.enum import try_parse_enum
 from homeassistant.util.hass_dict import HassKey
+from homeassistant.util.variance import ignore_variance
 
 from .const import (  # noqa: F401
     AMBIGUOUS_UNITS,
@@ -63,6 +64,8 @@ ENTITY_ID_FORMAT: Final = DOMAIN + ".{}"
 PLATFORM_SCHEMA = cv.PLATFORM_SCHEMA
 PLATFORM_SCHEMA_BASE = cv.PLATFORM_SCHEMA_BASE
 SCAN_INTERVAL: Final = timedelta(seconds=30)
+UPTIME_DEFAULT_TOLERANCE_SECONDS: Final = 60
+UPTIME_MIN_TOLERANCE_SECONDS: Final = 5
 
 __all__ = [
     "ATTR_LAST_RESET",
@@ -180,6 +183,9 @@ TEMPERATURE_UNITS = {UnitOfTemperature.CELSIUS, UnitOfTemperature.FAHRENHEIT}
 class SensorEntity(Entity, cached_properties=CACHED_PROPERTIES_WITH_ATTR_):
     """Base class for sensor entities."""
 
+    # Allow per-entity override of drift tolerance
+    _attr_uptime_drift_tolerance: int = UPTIME_DEFAULT_TOLERANCE_SECONDS
+
     _entity_component_unrecorded_attributes = frozenset({ATTR_OPTIONS})
 
     entity_description: SensorEntityDescription
@@ -201,6 +207,19 @@ class SensorEntity(Entity, cached_properties=CACHED_PROPERTIES_WITH_ATTR_):
     _sensor_option_display_precision: int | None = None
     _sensor_option_unit_of_measurement: str | None | UndefinedType = UNDEFINED
     _invalid_suggested_unit_of_measurement_reported = False
+    _get_uptime: Callable[[datetime], datetime] | None = None
+
+    def _normalize_uptime(self, current_uptime: datetime) -> datetime:
+        """Normalize uptime to suppress small drift between updates."""
+        if self._get_uptime is None:
+            drift_tolerance = max(
+                self._attr_uptime_drift_tolerance, UPTIME_MIN_TOLERANCE_SECONDS
+            )
+            self._get_uptime = ignore_variance(
+                func=lambda value: value,
+                ignored_variance=timedelta(seconds=drift_tolerance),
+            )
+        return self._get_uptime(current_uptime)
 
     @callback
     def add_to_platform_start(
@@ -610,10 +629,14 @@ class SensorEntity(Entity, cached_properties=CACHED_PROPERTIES_WITH_ATTR_):
 
         # Checks below only apply if there is a value
         if value is None:
+            if device_class is SensorDeviceClass.UPTIME:
+                # Reset baseline so the first uptime after unavailable is not
+                # compared against a stale value.
+                self._get_uptime = None
             return None
 
         # Received a datetime
-        if device_class is SensorDeviceClass.TIMESTAMP:
+        if device_class in (SensorDeviceClass.TIMESTAMP, SensorDeviceClass.UPTIME):
             try:
                 # We cast the value, to avoid using isinstance, but satisfy
                 # typechecking. The errors are guarded in this try.
@@ -627,10 +650,13 @@ class SensorEntity(Entity, cached_properties=CACHED_PROPERTIES_WITH_ATTR_):
                 if value.tzinfo != UTC:
                     value = value.astimezone(UTC)
 
+                if device_class is SensorDeviceClass.UPTIME:
+                    value = self._normalize_uptime(value)
+
                 return value.isoformat(timespec="seconds")
             except (AttributeError, OverflowError, TypeError) as err:
                 raise ValueError(
-                    f"Invalid datetime: {self.entity_id} has timestamp device class "
+                    f"Invalid datetime: {self.entity_id} has {device_class.value} device class "
                     f"but provides state {value}:{type(value)} resulting in '{err}'"
                 ) from err
 
diff --git a/homeassistant/components/sensor/const.py b/homeassistant/components/sensor/const.py
index 26fde2405969..85dd700e5ef1 100644
--- a/homeassistant/components/sensor/const.py
+++ b/homeassistant/components/sensor/const.py
@@ -117,6 +117,20 @@ class SensorDeviceClass(StrEnum):
     ISO8601 format: https://en.wikipedia.org/wiki/ISO_8601
     """
 
+    UPTIME = "uptime"
+    """Uptime.
+
+    Represents the point in time when a device or service last restarted.
+
+    Small drift between updates is automatically suppressed in
+    `SensorEntity.state` to avoid unnecessary state changes caused by clock
+    jitter.
+
+    Unit of measurement: `None`
+
+    ISO8601 format: https://en.wikipedia.org/wiki/ISO_8601
+    """
+
     # Numerical device classes, these should be aligned with NumberDeviceClass
     ABSOLUTE_HUMIDITY = "absolute_humidity"
     """Absolute humidity.
@@ -516,6 +530,7 @@ NON_NUMERIC_DEVICE_CLASSES = {
     SensorDeviceClass.DATE,
     SensorDeviceClass.ENUM,
     SensorDeviceClass.TIMESTAMP,
+    SensorDeviceClass.UPTIME,
 }
 
 DEVICE_CLASSES_SCHEMA: Final = vol.All(vol.Lower, vol.Coerce(SensorDeviceClass))
@@ -816,6 +831,7 @@ DEVICE_CLASS_STATE_CLASSES: dict[SensorDeviceClass, set[SensorStateClass]] = {
     SensorDeviceClass.TEMPERATURE: {SensorStateClass.MEASUREMENT},
     SensorDeviceClass.TEMPERATURE_DELTA: {SensorStateClass.MEASUREMENT},
     SensorDeviceClass.TIMESTAMP: set(),
+    SensorDeviceClass.UPTIME: set(),
     SensorDeviceClass.VOLATILE_ORGANIC_COMPOUNDS: {SensorStateClass.MEASUREMENT},
     SensorDeviceClass.VOLATILE_ORGANIC_COMPOUNDS_PARTS: {SensorStateClass.MEASUREMENT},
     SensorDeviceClass.VOLTAGE: {SensorStateClass.MEASUREMENT},
diff --git a/homeassistant/components/sensor/helpers.py b/homeassistant/components/sensor/helpers.py
index 12a5dcefdf8d..c404c697da00 100644
--- a/homeassistant/components/sensor/helpers.py
+++ b/homeassistant/components/sensor/helpers.py
@@ -18,7 +18,7 @@ def async_parse_date_datetime(
     value: str, entity_id: str, device_class: SensorDeviceClass | str | None
 ) -> datetime | date | None:
     """Parse datetime string to a data or datetime."""
-    if device_class == SensorDeviceClass.TIMESTAMP:
+    if device_class in (SensorDeviceClass.TIMESTAMP, SensorDeviceClass.UPTIME):
         if (parsed_timestamp := dt_util.parse_datetime(value)) is None:
             _LOGGER.warning("%s rendered invalid timestamp: %s", entity_id, value)
             return None
diff --git a/homeassistant/components/sensor/icons.json b/homeassistant/components/sensor/icons.json
index 59d57da28034..966e19439e38 100644
--- a/homeassistant/components/sensor/icons.json
+++ b/homeassistant/components/sensor/icons.json
@@ -163,6 +163,9 @@
     "timestamp": {
       "default": "mdi:clock"
     },
+    "uptime": {
+      "default": "mdi:clock-start"
+    },
     "volatile_organic_compounds": {
       "default": "mdi:molecule"
     },
diff --git a/homeassistant/components/sensor/strings.json b/homeassistant/components/sensor/strings.json
index 33b56f1b0f1d..e51c139e8dea 100644
--- a/homeassistant/components/sensor/strings.json
+++ b/homeassistant/components/sensor/strings.json
@@ -297,6 +297,9 @@
     "timestamp": {
       "name": "Timestamp"
     },
+    "uptime": {
+      "name": "Uptime"
+    },
     "volatile_organic_compounds": {
       "name": "Volatile organic compounds"
     },
diff --git a/homeassistant/helpers/condition.py b/homeassistant/helpers/condition.py
index 6d53f674188b..878c136c26c9 100644
--- a/homeassistant/helpers/condition.py
+++ b/homeassistant/helpers/condition.py
@@ -1476,7 +1476,7 @@ def time(
             after = datetime.strptime(after_entity.state, "%H:%M:%S").time()
         elif (
             after_entity.attributes.get(ATTR_DEVICE_CLASS)
-            == SensorDeviceClass.TIMESTAMP
+            in (SensorDeviceClass.TIMESTAMP, SensorDeviceClass.UPTIME)
         ) and after_entity.state not in (
             STATE_UNAVAILABLE,
             STATE_UNKNOWN,
@@ -1506,7 +1506,7 @@ def time(
                 return False
         elif (
             before_entity.attributes.get(ATTR_DEVICE_CLASS)
-            == SensorDeviceClass.TIMESTAMP
+            in (SensorDeviceClass.TIMESTAMP, SensorDeviceClass.UPTIME)
         ) and before_entity.state not in (
             STATE_UNAVAILABLE,
             STATE_UNKNOWN,
diff --git a/homeassistant/helpers/trigger_template_entity.py b/homeassistant/helpers/trigger_template_entity.py
index dc8f52763c32..87d03c011527 100644
--- a/homeassistant/helpers/trigger_template_entity.py
+++ b/homeassistant/helpers/trigger_template_entity.py
@@ -403,12 +403,13 @@ class ManualTriggerSensorEntity(ManualTriggerEntity, SensorEntity):
     def _set_native_value_with_possible_timestamp(self, value: Any) -> None:
         """Set native value with possible timestamp.
 
-        If self.device_class is `date` or `timestamp`,
+        If self.device_class is `date`, `timestamp`, or `uptime`,
         it will try to parse the value to a date/datetime object.
         """
         if self.device_class not in (
             SensorDeviceClass.DATE,
             SensorDeviceClass.TIMESTAMP,
+            SensorDeviceClass.UPTIME,
         ):
             self._attr_native_value = value
         elif value is not None:
diff --git a/tests/components/fritz/snapshots/test_sensor.ambr b/tests/components/fritz/snapshots/test_sensor.ambr
index d820dda43ee9..48ed12dec8fe 100644
--- a/tests/components/fritz/snapshots/test_sensor.ambr
+++ b/tests/components/fritz/snapshots/test_sensor.ambr
@@ -24,7 +24,7 @@
     'object_id_base': 'Connection uptime',
     'options': dict({
     }),
-    'original_device_class': <SensorDeviceClass.TIMESTAMP: 'timestamp'>,
+    'original_device_class': <SensorDeviceClass.UPTIME: 'uptime'>,
     'original_icon': None,
     'original_name': 'Connection uptime',
     'platform': 'fritz',
@@ -39,7 +39,7 @@
 # name: test_sensor_cpu_temp_not_supported[None-return_values1][sensor.mock_title_connection_uptime-state]
   StateSnapshot({
     'attributes': ReadOnlyDict({
-      'device_class': 'timestamp',
+      'device_class': 'uptime',
       'friendly_name': 'Mock Title Connection uptime',
     }),
     'context': <ANY>,
@@ -349,7 +349,7 @@
     'object_id_base': 'Last restart',
     'options': dict({
     }),
-    'original_device_class': <SensorDeviceClass.TIMESTAMP: 'timestamp'>,
+    'original_device_class': <SensorDeviceClass.UPTIME: 'uptime'>,
     'original_icon': None,
     'original_name': 'Last restart',
     'platform': 'fritz',
@@ -364,7 +364,7 @@
 # name: test_sensor_cpu_temp_not_supported[None-return_values1][sensor.mock_title_last_restart-state]
   StateSnapshot({
     'attributes': ReadOnlyDict({
-      'device_class': 'timestamp',
+      'device_class': 'uptime',
       'friendly_name': 'Mock Title Last restart',
     }),
     'context': <ANY>,
@@ -882,7 +882,7 @@
     'object_id_base': 'Connection uptime',
     'options': dict({
     }),
-    'original_device_class': <SensorDeviceClass.TIMESTAMP: 'timestamp'>,
+    'original_device_class': <SensorDeviceClass.UPTIME: 'uptime'>,
     'original_icon': None,
     'original_name': 'Connection uptime',
     'platform': 'fritz',
@@ -897,7 +897,7 @@
 # name: test_sensor_cpu_temp_not_supported[None-return_values2][sensor.mock_title_connection_uptime-state]
   StateSnapshot({
     'attributes': ReadOnlyDict({
-      'device_class': 'timestamp',
+      'device_class': 'uptime',
       'friendly_name': 'Mock Title Connection uptime',
     }),
     'context': <ANY>,
@@ -1207,7 +1207,7 @@
     'object_id_base': 'Last restart',
     'options': dict({
     }),
-    'original_device_class': <SensorDeviceClass.TIMESTAMP: 'timestamp'>,
+    'original_device_class': <SensorDeviceClass.UPTIME: 'uptime'>,
     'original_icon': None,
     'original_name': 'Last restart',
     'platform': 'fritz',
@@ -1222,7 +1222,7 @@
 # name: test_sensor_cpu_temp_not_supported[None-return_values2][sensor.mock_title_last_restart-state]
   StateSnapshot({
     'attributes': ReadOnlyDict({
-      'device_class': 'timestamp',
+      'device_class': 'uptime',
       'friendly_name': 'Mock Title Last restart',
     }),
     'context': <ANY>,
@@ -1740,7 +1740,7 @@
     'object_id_base': 'Connection uptime',
     'options': dict({
     }),
-    'original_device_class': <SensorDeviceClass.TIMESTAMP: 'timestamp'>,
+    'original_device_class': <SensorDeviceClass.UPTIME: 'uptime'>,
     'original_icon': None,
     'original_name': 'Connection uptime',
     'platform': 'fritz',
@@ -1755,7 +1755,7 @@
 # name: test_sensor_cpu_temp_not_supported[side_effect0-None][sensor.mock_title_connection_uptime-state]
   StateSnapshot({
     'attributes': ReadOnlyDict({
-      'device_class': 'timestamp',
+      'device_class': 'uptime',
       'friendly_name': 'Mock Title Connection uptime',
     }),
     'context': <ANY>,
@@ -2065,7 +2065,7 @@
     'object_id_base': 'Last restart',
     'options': dict({
     }),
-    'original_device_class': <SensorDeviceClass.TIMESTAMP: 'timestamp'>,
+    'original_device_class': <SensorDeviceClass.UPTIME: 'uptime'>,
     'original_icon': None,
     'original_name': 'Last restart',
     'platform': 'fritz',
@@ -2080,7 +2080,7 @@
 # name: test_sensor_cpu_temp_not_supported[side_effect0-None][sensor.mock_title_last_restart-state]
   StateSnapshot({
     'attributes': ReadOnlyDict({
-      'device_class': 'timestamp',
+      'device_class': 'uptime',
       'friendly_name': 'Mock Title Last restart',
     }),
     'context': <ANY>,
@@ -2598,7 +2598,7 @@
     'object_id_base': 'Connection uptime',
     'options': dict({
     }),
-    'original_device_class': <SensorDeviceClass.TIMESTAMP: 'timestamp'>,
+    'original_device_class': <SensorDeviceClass.UPTIME: 'uptime'>,
     'original_icon': None,
     'original_name': 'Connection uptime',
     'platform': 'fritz',
@@ -2613,7 +2613,7 @@
 # name: test_sensor_setup[sensor.mock_title_connection_uptime-state]
   StateSnapshot({
     'attributes': ReadOnlyDict({
-      'device_class': 'timestamp',
+      'device_class': 'uptime',
       'friendly_name': 'Mock Title Connection uptime',
     }),
     'context': <ANY>,
@@ -2981,7 +2981,7 @@
     'object_id_base': 'Last restart',
     'options': dict({
     }),
-    'original_device_class': <SensorDeviceClass.TIMESTAMP: 'timestamp'>,
+    'original_device_class': <SensorDeviceClass.UPTIME: 'uptime'>,
     'original_icon': None,
     'original_name': 'Last restart',
     'platform': 'fritz',
@@ -2996,7 +2996,7 @@
 # name: test_sensor_setup[sensor.mock_title_last_restart-state]
   StateSnapshot({
     'attributes': ReadOnlyDict({
-      'device_class': 'timestamp',
+      'device_class': 'uptime',
       'friendly_name': 'Mock Title Last restart',
     }),
     'context': <ANY>,
diff --git a/tests/components/fritz/test_sensor.py b/tests/components/fritz/test_sensor.py
index d00327994d63..94cb74f63a0e 100644
--- a/tests/components/fritz/test_sensor.py
+++ b/tests/components/fritz/test_sensor.py
@@ -11,7 +11,7 @@ import pytest
 from requests.exceptions import RequestException
 from syrupy.assertion import SnapshotAssertion
 
-from homeassistant.components.fritz.const import DOMAIN, SCAN_INTERVAL, UPTIME_DEVIATION
+from homeassistant.components.fritz.const import DOMAIN, SCAN_INTERVAL
 from homeassistant.components.sensor import DOMAIN as SENSOR_DOMAIN
 from homeassistant.const import STATE_UNAVAILABLE, Platform
 from homeassistant.core import HomeAssistant
@@ -95,13 +95,13 @@ async def test_sensor_uptime_spike(
     assert (state := hass.states.get(entity_id))
     assert state.state == "2026-01-16T06:00:21+00:00"
 
-    # Simulate uptime spike by setting uptime to a value between
-    # the previous one and a delta smaller than UPTIME_DEVIATION
+    # Simulate uptime spike by setting uptime to a value that shifts
+    # the resulting timestamp only by 1 second.
     base_uptime = MOCK_FB_SERVICES["DeviceInfo1"]["GetInfo"]["NewUpTime"]
     update_uptime = {
         "DeviceInfo1": {
             "GetInfo": {
-                "NewUpTime": base_uptime + SCAN_INTERVAL - UPTIME_DEVIATION + 1,
+                "NewUpTime": base_uptime + SCAN_INTERVAL + 1,
             },
         },
     }
diff --git a/tests/components/homeassistant/triggers/test_time.py b/tests/components/homeassistant/triggers/test_time.py
index dc9fb1d34c27..79f07c5285d3 100644
--- a/tests/components/homeassistant/triggers/test_time.py
+++ b/tests/components/homeassistant/triggers/test_time.py
@@ -521,11 +521,16 @@ async def test_untrack_time_change(hass: HomeAssistant) -> None:
 @pytest.mark.parametrize(
     ("at_sensor"), ["sensor.next_alarm", "{{ 'sensor.next_alarm' }}"]
 )
+@pytest.mark.parametrize(
+    "device_class",
+    [SensorDeviceClass.TIMESTAMP, SensorDeviceClass.UPTIME],
+)
 async def test_if_fires_using_at_sensor(
     hass: HomeAssistant,
     freezer: FrozenDateTimeFactory,
     service_calls: list[ServiceCall],
     at_sensor: str,
+    device_class: SensorDeviceClass,
 ) -> None:
     """Test for firing at sensor time."""
     now = dt_util.now()
@@ -535,7 +540,7 @@ async def test_if_fires_using_at_sensor(
     hass.states.async_set(
         "sensor.next_alarm",
         trigger_dt.isoformat(),
-        {ATTR_DEVICE_CLASS: SensorDeviceClass.TIMESTAMP},
+        {ATTR_DEVICE_CLASS: device_class},
     )
 
     time_that_will_not_match_right_away = trigger_dt - timedelta(minutes=1)
@@ -572,7 +577,7 @@ async def test_if_fires_using_at_sensor(
     hass.states.async_set(
         "sensor.next_alarm",
         trigger_dt.isoformat(),
-        {ATTR_DEVICE_CLASS: SensorDeviceClass.TIMESTAMP},
+        {ATTR_DEVICE_CLASS: device_class},
     )
     await hass.async_block_till_done()
 
@@ -589,13 +594,13 @@ async def test_if_fires_using_at_sensor(
         hass.states.async_set(
             "sensor.next_alarm",
             trigger_dt.isoformat(),
-            {ATTR_DEVICE_CLASS: SensorDeviceClass.TIMESTAMP},
+            {ATTR_DEVICE_CLASS: device_class},
         )
         await hass.async_block_till_done()
         hass.states.async_set(
             "sensor.next_alarm",
             broken,
-            {ATTR_DEVICE_CLASS: SensorDeviceClass.TIMESTAMP},
+            {ATTR_DEVICE_CLASS: device_class},
         )
         await hass.async_block_till_done()
 
@@ -609,7 +614,7 @@ async def test_if_fires_using_at_sensor(
     hass.states.async_set(
         "sensor.next_alarm",
         trigger_dt.isoformat(),
-        {ATTR_DEVICE_CLASS: SensorDeviceClass.TIMESTAMP},
+        {ATTR_DEVICE_CLASS: device_class},
     )
     await hass.async_block_till_done()
     hass.states.async_set(
@@ -633,12 +638,17 @@ async def test_if_fires_using_at_sensor(
         ({"minutes": 5}, timedelta(minutes=5)),
     ],
 )
+@pytest.mark.parametrize(
+    "device_class",
+    [SensorDeviceClass.TIMESTAMP, SensorDeviceClass.UPTIME],
+)
 async def test_if_fires_using_at_sensor_with_offset(
     hass: HomeAssistant,
     service_calls: list[ServiceCall],
     freezer: FrozenDateTimeFactory,
     offset: str | dict[str, int],
     delta: timedelta,
+    device_class: SensorDeviceClass,
 ) -> None:
     """Test for firing at sensor time."""
     now = dt_util.now()
@@ -649,7 +659,7 @@ async def test_if_fires_using_at_sensor_with_offset(
     hass.states.async_set(
         "sensor.next_alarm",
         start_dt.isoformat(),
-        {ATTR_DEVICE_CLASS: SensorDeviceClass.TIMESTAMP},
+        {ATTR_DEVICE_CLASS: device_class},
     )
 
     time_that_will_not_match_right_away = trigger_dt - timedelta(minutes=1)
@@ -693,7 +703,7 @@ async def test_if_fires_using_at_sensor_with_offset(
     hass.states.async_set(
         "sensor.next_alarm",
         start_dt.isoformat(),
-        {ATTR_DEVICE_CLASS: SensorDeviceClass.TIMESTAMP},
+        {ATTR_DEVICE_CLASS: device_class},
     )
     await hass.async_block_till_done()
 
diff --git a/tests/components/knx/snapshots/test_websocket.ambr b/tests/components/knx/snapshots/test_websocket.ambr
index cfc5ec81064d..49299a9537a4 100644
--- a/tests/components/knx/snapshots/test_websocket.ambr
+++ b/tests/components/knx/snapshots/test_websocket.ambr
@@ -2216,6 +2216,7 @@
             'options': list([
               'date',
               'timestamp',
+              'uptime',
               'absolute_humidity',
               'apparent_power',
               'aqi',
diff --git a/tests/components/sensor/common.py b/tests/components/sensor/common.py
index 4dedababad1c..3721e7be2206 100644
--- a/tests/components/sensor/common.py
+++ b/tests/components/sensor/common.py
@@ -95,6 +95,7 @@ UNITS_OF_MEASUREMENT = {
     SensorDeviceClass.TEMPERATURE: UnitOfTemperature.CELSIUS,
     SensorDeviceClass.TEMPERATURE_DELTA: UnitOfTemperature.CELSIUS,
     SensorDeviceClass.TIMESTAMP: None,
+    SensorDeviceClass.UPTIME: None,
     SensorDeviceClass.VOLATILE_ORGANIC_COMPOUNDS: CONCENTRATION_MICROGRAMS_PER_CUBIC_METER,
     SensorDeviceClass.VOLATILE_ORGANIC_COMPOUNDS_PARTS: CONCENTRATION_PARTS_PER_MILLION,
     SensorDeviceClass.VOLTAGE: UnitOfElectricPotential.VOLT,
diff --git a/tests/components/sensor/test_device_condition.py b/tests/components/sensor/test_device_condition.py
index 67f07e3293a3..59aeb8cc8d53 100644
--- a/tests/components/sensor/test_device_condition.py
+++ b/tests/components/sensor/test_device_condition.py
@@ -101,6 +101,7 @@ async def test_get_conditions(
         SensorDeviceClass.DATE,
         SensorDeviceClass.ENUM,
         SensorDeviceClass.TIMESTAMP,
+        SensorDeviceClass.UPTIME,
     }
     expected_conditions = [
         {
@@ -202,6 +203,7 @@ async def test_get_conditions_no_state(
         SensorDeviceClass.DATE,  # No condition
         SensorDeviceClass.ENUM,  # No condition
         SensorDeviceClass.TIMESTAMP,  # No condition
+        SensorDeviceClass.UPTIME,  # No condition
         SensorDeviceClass.AQI,  # No unit of measurement
         SensorDeviceClass.PH,  # No unit of measurement
         SensorDeviceClass.MONETARY,  # No unit of measurement
diff --git a/tests/components/sensor/test_device_trigger.py b/tests/components/sensor/test_device_trigger.py
index 8b407ac5576c..d796dd1158a6 100644
--- a/tests/components/sensor/test_device_trigger.py
+++ b/tests/components/sensor/test_device_trigger.py
@@ -103,6 +103,7 @@ async def test_get_triggers(
         SensorDeviceClass.DATE,
         SensorDeviceClass.ENUM,
         SensorDeviceClass.TIMESTAMP,
+        SensorDeviceClass.UPTIME,
     }
     expected_triggers = [
         {
diff --git a/tests/components/sensor/test_helpers.py b/tests/components/sensor/test_helpers.py
index e197579fa667..2fc89f258557 100644
--- a/tests/components/sensor/test_helpers.py
+++ b/tests/components/sensor/test_helpers.py
@@ -6,10 +6,15 @@ from homeassistant.components.sensor import SensorDeviceClass
 from homeassistant.components.sensor.helpers import async_parse_date_datetime
 
 
-def test_async_parse_datetime(caplog: pytest.LogCaptureFixture) -> None:
+@pytest.mark.parametrize(
+    "device_class",
+    [SensorDeviceClass.TIMESTAMP, SensorDeviceClass.UPTIME],
+)
+def test_async_parse_datetime(
+    caplog: pytest.LogCaptureFixture, device_class: SensorDeviceClass
+) -> None:
     """Test async_parse_date_datetime."""
     entity_id = "sensor.timestamp"
-    device_class = SensorDeviceClass.TIMESTAMP
     assert (
         async_parse_date_datetime(
             "2021-12-12 12:12Z", entity_id, device_class
diff --git a/tests/components/sensor/test_init.py b/tests/components/sensor/test_init.py
index e9ae2ba4f752..3a03a608ce88 100644
--- a/tests/components/sensor/test_init.py
+++ b/tests/components/sensor/test_init.py
@@ -3,7 +3,7 @@
 from __future__ import annotations
 
 from collections.abc import Generator
-from datetime import UTC, date, datetime
+from datetime import UTC, date, datetime, timedelta
 from decimal import Decimal
 import math
 from typing import Any
@@ -23,6 +23,7 @@ from homeassistant.components.sensor import (
     DEVICE_CLASS_UNITS,
     DOMAIN,
     NON_NUMERIC_DEVICE_CLASSES,
+    UPTIME_DEFAULT_TOLERANCE_SECONDS,
     SensorDeviceClass,
     SensorEntity,
     SensorEntityDescription,
@@ -283,6 +284,44 @@ async def test_datetime_conversion(
     assert state.state == test_timestamp.isoformat()
 
 
+@pytest.mark.parametrize("drift_tolerance", [UPTIME_DEFAULT_TOLERANCE_SECONDS, 10])
+async def test_uptime_device_class_auto_normalizes_drift(
+    hass: HomeAssistant, drift_tolerance
+) -> None:
+    """Test uptime device class suppresses small drift automatically."""
+    initial_uptime = datetime(2026, 2, 14, 9, 30, tzinfo=UTC)
+    entity = MockSensor(
+        name="Test",
+        native_value=initial_uptime,
+        device_class=SensorDeviceClass.UPTIME,
+    )
+    entity._attr_uptime_drift_tolerance = drift_tolerance
+    setup_test_component_platform(hass, sensor.DOMAIN, [entity])
+
+    assert await async_setup_component(hass, "sensor", {"sensor": {"platform": "test"}})
+    await hass.async_block_till_done()
+
+    assert (state := hass.states.get(entity.entity_id))
+    assert state.state == initial_uptime.isoformat(timespec="seconds")
+
+    entity._values["native_value"] = initial_uptime + timedelta(
+        seconds=drift_tolerance - 1
+    )
+    entity.async_write_ha_state()
+    await hass.async_block_till_done()
+
+    assert (state := hass.states.get(entity.entity_id))
+    assert state.state == initial_uptime.isoformat(timespec="seconds")
+
+    updated_uptime = initial_uptime + timedelta(seconds=drift_tolerance + 1)
+    entity._values["native_value"] = updated_uptime
+    entity.async_write_ha_state()
+    await hass.async_block_till_done()
+
+    assert (state := hass.states.get(entity.entity_id))
+    assert state.state == updated_uptime.isoformat(timespec="seconds")
+
+
 async def test_a_sensor_with_a_non_numeric_device_class(
     hass: HomeAssistant,
     caplog: pytest.LogCaptureFixture,
@@ -2200,6 +2239,7 @@ async def test_invalid_enumeration_entity_without_device_class(
         SensorDeviceClass.DATE,
         SensorDeviceClass.ENUM,
         SensorDeviceClass.TIMESTAMP,
+        SensorDeviceClass.UPTIME,
     ],
 )
 async def test_non_numeric_device_class_with_unit_of_measurement(
@@ -2554,6 +2594,7 @@ async def test_device_classes_with_invalid_state_class(
         (SensorDeviceClass.ENUM, None, None, None, False),
         (SensorDeviceClass.DATE, None, None, None, False),
         (SensorDeviceClass.TIMESTAMP, None, None, None, False),
+        (SensorDeviceClass.UPTIME, None, None, None, False),
         ("custom", None, None, None, False),
         (SensorDeviceClass.POWER, None, "V", None, True),
         (None, SensorStateClass.MEASUREMENT, None, None, True),
@@ -3097,6 +3138,7 @@ def test_device_class_units_are_complete() -> None:
         SensorDeviceClass.ENUM,
         SensorDeviceClass.MONETARY,
         SensorDeviceClass.TIMESTAMP,
+        SensorDeviceClass.UPTIME,
     }
     unit_device_classes = {
         device_class.value for device_class in SensorDeviceClass
@@ -3126,6 +3168,7 @@ def test_device_class_converters_are_complete() -> None:
         SensorDeviceClass.SIGNAL_STRENGTH,
         SensorDeviceClass.SOUND_PRESSURE,
         SensorDeviceClass.TIMESTAMP,
+        SensorDeviceClass.UPTIME,
         SensorDeviceClass.WIND_DIRECTION,
     }
     converter_device_classes = {
diff --git a/tests/helpers/test_condition.py b/tests/helpers/test_condition.py
index be995e352487..cec1e5976e28 100644
--- a/tests/helpers/test_condition.py
+++ b/tests/helpers/test_condition.py
@@ -1146,6 +1146,11 @@ async def test_time_using_sensor(hass: HomeAssistant) -> None:
         "2020-06-01 01:00:00.000000+00:00",  # 6 pm local time
         {ATTR_DEVICE_CLASS: SensorDeviceClass.TIMESTAMP},
     )
+    hass.states.async_set(
+        "sensor.uptime_am",
+        "2021-06-03 13:00:00.000000+00:00",  # 6 am local time
+        {ATTR_DEVICE_CLASS: SensorDeviceClass.UPTIME},
+    )
     hass.states.async_set(
         "sensor.no_device_class",
         "2020-06-01 01:00:00.000000+00:00",
@@ -1168,6 +1173,7 @@ async def test_time_using_sensor(hass: HomeAssistant) -> None:
         return_value=dt_util.now().replace(hour=9),
     ):
         assert condition.time(hass, after="sensor.am", before="sensor.pm")
+        assert condition.time(hass, after="sensor.uptime_am", before="sensor.pm")
         assert not condition.time(hass, after="sensor.pm", before="sensor.am")
 
     with patch(
diff --git a/tests/helpers/test_trigger_template_entity.py b/tests/helpers/test_trigger_template_entity.py
index 08f6c7de8197..0bbe521eef00 100644
--- a/tests/helpers/test_trigger_template_entity.py
+++ b/tests/helpers/test_trigger_template_entity.py
@@ -296,14 +296,20 @@ async def test_trigger_template_complex(hass: HomeAssistant) -> None:
     assert entity.some_other_key == {"test_key": "test_data"}
 
 
+@pytest.mark.parametrize(
+    "device_class",
+    [SensorDeviceClass.TIMESTAMP, SensorDeviceClass.UPTIME],
+)
 async def test_manual_trigger_sensor_entity_with_date(
-    hass: HomeAssistant, caplog: pytest.LogCaptureFixture
+    hass: HomeAssistant,
+    caplog: pytest.LogCaptureFixture,
+    device_class: SensorDeviceClass,
 ) -> None:
     """Test manual trigger template entity when availability template isn't used."""
     config = {
         CONF_NAME: template.Template("test_entity", hass),
         CONF_STATE: template.Template("{{ as_datetime(value) }}", hass),
-        CONF_DEVICE_CLASS: SensorDeviceClass.TIMESTAMP,
+        CONF_DEVICE_CLASS: device_class,
     }
 
     class TestEntity(ManualTriggerSensorEntity):
@@ -328,4 +334,4 @@ async def test_manual_trigger_sensor_entity_with_date(
         "2025-01-01T00:00:00+00:00", entity.entity_id, entity.device_class
     )
     assert entity.state == "2025-01-01T00:00:00+00:00"
-    assert entity.device_class == SensorDeviceClass.TIMESTAMP
+    assert entity.device_class == device_class