diff --git a/homeassistant/components/mcp/__init__.py b/homeassistant/components/mcp/__init__.py
index 642fa400213..c4238017564 100644
--- a/homeassistant/components/mcp/__init__.py
+++ b/homeassistant/components/mcp/__init__.py
@@ -7,6 +7,7 @@ from typing import cast
 
 from homeassistant.components.application_credentials import AuthorizationServer
 from homeassistant.core import HomeAssistant
+from homeassistant.exceptions import ConfigEntryNotReady
 from homeassistant.helpers import config_entry_oauth2_flow, llm
 
 from .application_credentials import authorization_server_context
@@ -42,7 +43,14 @@ async def _create_token_manager(
     hass: HomeAssistant, entry: ModelContextProtocolConfigEntry
 ) -> TokenManager | None:
     """Create a OAuth token manager for the config entry if the server requires authentication."""
-    if not (implementation := await async_get_config_entry_implementation(hass, entry)):
+    try:
+        implementation = await async_get_config_entry_implementation(hass, entry)
+    except config_entry_oauth2_flow.ImplementationUnavailableError as err:
+        raise ConfigEntryNotReady(
+            translation_domain=DOMAIN,
+            translation_key="oauth2_implementation_unavailable",
+        ) from err
+    if not implementation:
         return None
 
     session = config_entry_oauth2_flow.OAuth2Session(hass, entry, implementation)
diff --git a/homeassistant/components/mcp/strings.json b/homeassistant/components/mcp/strings.json
index 1dcc4400ced..c5e84505b41 100644
--- a/homeassistant/components/mcp/strings.json
+++ b/homeassistant/components/mcp/strings.json
@@ -56,5 +56,10 @@
         }
       }
     }
+  },
+  "exceptions": {
+    "oauth2_implementation_unavailable": {
+      "message": "[%key:common::exceptions::oauth2_implementation_unavailable::message%]"
+    }
   }
 }
diff --git a/tests/components/mcp/test_init.py b/tests/components/mcp/test_init.py
index 1f063e445ee..0a1f67e1336 100644
--- a/tests/components/mcp/test_init.py
+++ b/tests/components/mcp/test_init.py
@@ -13,6 +13,9 @@ from homeassistant.config_entries import ConfigEntryState
 from homeassistant.core import Context, HomeAssistant
 from homeassistant.exceptions import HomeAssistantError
 from homeassistant.helpers import llm
+from homeassistant.helpers.config_entry_oauth2_flow import (
+    ImplementationUnavailableError,
+)
 
 from .conftest import TEST_API_NAME
 
@@ -342,3 +345,19 @@ async def test_convert_tool_schema_fails(
     ):
         await hass.config_entries.async_setup(config_entry.entry_id)
         assert config_entry.state is ConfigEntryState.SETUP_RETRY
+
+
+async def test_oauth_implementation_not_available(
+    hass: HomeAssistant,
+    config_entry_with_auth: MockConfigEntry,
+    mock_mcp_client: AsyncMock,
+) -> None:
+    """Test that unavailable OAuth implementation raises ConfigEntryNotReady."""
+    with patch(
+        "homeassistant.components.mcp.async_get_config_entry_implementation",
+        side_effect=ImplementationUnavailableError,
+    ):
+        await hass.config_entries.async_setup(config_entry_with_auth.entry_id)
+        await hass.async_block_till_done()
+
+    assert config_entry_with_auth.state is ConfigEntryState.SETUP_RETRY