diff --git a/homeassistant/components/homematicip_cloud/hap.py b/homeassistant/components/homematicip_cloud/hap.py
index ad0699f5d89a..de71dfe03334 100644
--- a/homeassistant/components/homematicip_cloud/hap.py
+++ b/homeassistant/components/homematicip_cloud/hap.py
@@ -105,6 +105,9 @@ class HomematicipAuth:
             _LOGGER.debug("Connection request result: %s", result)
         except HmipConnectionError:
             return None
+        # a rejected SGTIN or PIN comes back as a failed result, not an exception
+        if not result.success:
+            return None
         return auth
 
 
diff --git a/tests/components/homematicip_cloud/test_config_flow.py b/tests/components/homematicip_cloud/test_config_flow.py
index fedf7902a392..4fd0e67ba1c0 100644
--- a/tests/components/homematicip_cloud/test_config_flow.py
+++ b/tests/components/homematicip_cloud/test_config_flow.py
@@ -1,6 +1,9 @@
 """Tests for HomematicIP Cloud config flow."""
 
-from unittest.mock import patch
+from unittest.mock import AsyncMock, patch
+
+from homematicip.connection.connection_context import ConnectionContext
+from homematicip.connection.rest_connection import RestResult
 
 from homeassistant import config_entries
 from homeassistant.components.homematicip_cloud.const import (
@@ -104,6 +107,37 @@ async def test_flow_init_connection_error(hass: HomeAssistant) -> None:
     assert result["errors"] == {"base": "invalid_sgtin_or_pin"}
 
 
+async def test_flow_init_rejected_pin(
+    hass: HomeAssistant, simple_mock_auth: AsyncMock
+) -> None:
+    """Test the flow stays on the first step when the cloud rejects the PIN."""
+    result = await hass.config_entries.flow.async_init(
+        DOMAIN, context={"source": config_entries.SOURCE_USER}
+    )
+
+    # the library hands a 400 back as a failed result instead of raising
+    simple_mock_auth.connection_request.return_value = RestResult(
+        status=400, text='{"errorCode":"INVALID_PIN"}'
+    )
+    with (
+        patch(
+            "homeassistant.components.homematicip_cloud.hap.Auth",
+            return_value=simple_mock_auth,
+        ),
+        patch(
+            "homeassistant.components.homematicip_cloud.hap.ConnectionContextBuilder.build_context_async",
+            return_value=ConnectionContext(),
+        ),
+    ):
+        result = await hass.config_entries.flow.async_configure(
+            result["flow_id"], user_input=DEFAULT_CONFIG
+        )
+
+    assert result["type"] is FlowResultType.FORM
+    assert result["step_id"] == "init"
+    assert result["errors"] == {"base": "invalid_sgtin_or_pin"}
+
+
 async def test_flow_link_connection_error(hass: HomeAssistant) -> None:
     """Test config flow client registration connection error."""
     result = await hass.config_entries.flow.async_init(
diff --git a/tests/components/homematicip_cloud/test_hap.py b/tests/components/homematicip_cloud/test_hap.py
index 1fa4b859097e..48ed9e9ffb79 100644
--- a/tests/components/homematicip_cloud/test_hap.py
+++ b/tests/components/homematicip_cloud/test_hap.py
@@ -5,6 +5,7 @@ from unittest.mock import AsyncMock, MagicMock, Mock, patch
 
 from homematicip.auth import Auth
 from homematicip.connection.connection_context import ConnectionContext
+from homematicip.connection.rest_connection import RestResult
 from homematicip.exceptions.connection_exceptions import (
     HmipAuthenticationError,
     HmipConnectionError,
@@ -197,6 +198,7 @@ async def test_auth_create(hass: HomeAssistant, simple_mock_auth) -> None:
     """Mock AsyncAuth to execute get_auth."""
     config = {HMIPC_HAPID: HAPID, HMIPC_PIN: HAPPIN, HMIPC_NAME: "hmip"}
     hmip_auth = HomematicipAuth(hass, config)
+    simple_mock_auth.connection_request.return_value = RestResult(status=200)
     assert hmip_auth
 
     with (
@@ -245,6 +247,29 @@ async def test_auth_create_exception(hass: HomeAssistant, simple_mock_auth) -> N
         assert not await hmip_auth.get_auth(hass, HAPID, HAPPIN)
 
 
+async def test_auth_create_rejected(
+    hass: HomeAssistant, simple_mock_auth: AsyncMock
+) -> None:
+    """Test a connection request the cloud rejects does not yield an auth."""
+    config = {HMIPC_HAPID: HAPID, HMIPC_PIN: HAPPIN, HMIPC_NAME: "hmip"}
+    hmip_auth = HomematicipAuth(hass, config)
+    # a wrong or missing PIN is answered with a 400, which the library returns
+    simple_mock_auth.connection_request.return_value = RestResult(
+        status=400, text='{"errorCode":"INVALID_PIN"}'
+    )
+    with (
+        patch(
+            "homeassistant.components.homematicip_cloud.hap.Auth",
+            return_value=simple_mock_auth,
+        ),
+        patch(
+            "homeassistant.components.homematicip_cloud.hap.ConnectionContextBuilder.build_context_async",
+            return_value=ConnectionContext(),
+        ),
+    ):
+        assert not await hmip_auth.async_setup()
+
+
 async def test_get_state_after_disconnect(
     hass: HomeAssistant, hmip_config_entry: MockConfigEntry, simple_mock_home
 ) -> None: