diff --git a/homeassistant/components/denonavr/media_player.py b/homeassistant/components/denonavr/media_player.py
index ee02e7390ebc..cf697b993cec 100644
--- a/homeassistant/components/denonavr/media_player.py
+++ b/homeassistant/components/denonavr/media_player.py
@@ -20,6 +20,8 @@ from denonavr.const import (
 from denonavr.exceptions import (
     AvrCommandError,
     AvrForbiddenError,
+    AvrIncompleteResponseError,
+    AvrInvalidResponseError,
     AvrNetworkError,
     AvrProcessingError,
     AvrTimoutError,
@@ -191,6 +193,17 @@ def async_log_errors[_DenonDeviceT: DenonDevice, **_P, _R](
                     self._receiver.host,
                 )
                 self._attr_available = False
+        except AvrInvalidResponseError, AvrIncompleteResponseError:
+            available = False
+            if self.available:
+                _LOGGER.warning(
+                    (
+                        "Denon AVR receiver at host %s returned malformed response. "
+                        "Device is unavailable"
+                    ),
+                    self._receiver.host,
+                )
+                self._attr_available = False
         except AvrCommandError as err:
             available = False
             _LOGGER.error(
diff --git a/tests/components/denonavr/test_media_player.py b/tests/components/denonavr/test_media_player.py
index 24b12c085074..662334a96968 100644
--- a/tests/components/denonavr/test_media_player.py
+++ b/tests/components/denonavr/test_media_player.py
@@ -1,7 +1,10 @@
 """The tests for the denonavr media player platform."""
 
+from datetime import timedelta
 from unittest.mock import patch
 
+from denonavr.exceptions import AvrIncompleteResponseError, AvrInvalidResponseError
+from freezegun.api import FrozenDateTimeFactory
 import pytest
 
 from homeassistant.components import media_player
@@ -18,10 +21,10 @@ from homeassistant.components.denonavr.services import (
     SERVICE_SET_DYNAMIC_EQ,
     SERVICE_UPDATE_AUDYSSEY,
 )
-from homeassistant.const import ATTR_ENTITY_ID, CONF_HOST, CONF_MODEL
+from homeassistant.const import ATTR_ENTITY_ID, CONF_HOST, CONF_MODEL, STATE_UNAVAILABLE
 from homeassistant.core import HomeAssistant
 
-from tests.common import MockConfigEntry
+from tests.common import MockConfigEntry, async_fire_time_changed
 
 TEST_HOST = "1.2.3.4"
 TEST_NAME = "Test_Receiver"
@@ -137,3 +140,40 @@ async def test_update_audyssey(hass: HomeAssistant, client) -> None:
     await hass.async_block_till_done()
 
     client.async_update_audyssey.assert_called_once()
+
+
+@pytest.mark.parametrize(
+    "exception",
+    [
+        pytest.param(
+            AvrInvalidResponseError("XML parse error", "GET"),
+            id="invalid_response",
+        ),
+        pytest.param(
+            AvrIncompleteResponseError("Incomplete", "GET"),
+            id="incomplete_response",
+        ),
+    ],
+)
+async def test_malformed_response_marks_unavailable(
+    hass: HomeAssistant,
+    client,
+    freezer: FrozenDateTimeFactory,
+    exception: Exception,
+) -> None:
+    """Test that malformed response errors mark the entity unavailable."""
+    await setup_denonavr(hass)
+
+    state = hass.states.get(ENTITY_ID)
+    assert state.state != STATE_UNAVAILABLE
+
+    # Force polling by disabling telnet, then trigger the error
+    client.telnet_connected = False
+    client.telnet_healthy = False
+    client.async_update.side_effect = exception
+    freezer.tick(timedelta(seconds=11))
+    async_fire_time_changed(hass)
+    await hass.async_block_till_done()
+
+    state = hass.states.get(ENTITY_ID)
+    assert state.state == STATE_UNAVAILABLE