diff --git a/.strict-typing b/.strict-typing
index 1d73b05fdea..e93f1589cc8 100644
--- a/.strict-typing
+++ b/.strict-typing
@@ -341,6 +341,7 @@ homeassistant.components.nut.*
 homeassistant.components.onboarding.*
 homeassistant.components.oncue.*
 homeassistant.components.onewire.*
+homeassistant.components.onkyo.*
 homeassistant.components.open_meteo.*
 homeassistant.components.openexchangerates.*
 homeassistant.components.opensky.*
diff --git a/homeassistant/components/onkyo/media_player.py b/homeassistant/components/onkyo/media_player.py
index df1f25a196b..1718ecb36be 100644
--- a/homeassistant/components/onkyo/media_player.py
+++ b/homeassistant/components/onkyo/media_player.py
@@ -4,7 +4,7 @@ from __future__ import annotations
 
 import asyncio
 import logging
-from typing import Any
+from typing import Any, Literal
 
 import pyeiscp
 import voluptuous as vol
@@ -23,7 +23,7 @@ from homeassistant.const import (
     CONF_NAME,
     EVENT_HOMEASSISTANT_STOP,
 )
-from homeassistant.core import HomeAssistant, ServiceCall, callback
+from homeassistant.core import Event, HomeAssistant, ServiceCall, callback
 from homeassistant.helpers import config_validation as cv
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
 from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
@@ -269,7 +269,7 @@ async def async_setup_platform(
         _LOGGER.debug("Manually creating receiver: %s (%s)", name, host)
 
         @callback
-        async def async_onkyo_interview_callback(conn: pyeiscp.Connection):
+        async def async_onkyo_interview_callback(conn: pyeiscp.Connection) -> None:
             """Receiver interviewed, connection not yet active."""
             info = ReceiverInfo(conn.host, conn.port, conn.name, conn.identifier)
             _LOGGER.debug("Receiver interviewed: %s (%s)", info.model_name, info.host)
@@ -285,7 +285,7 @@ async def async_setup_platform(
         _LOGGER.debug("Discovering receivers")
 
         @callback
-        async def async_onkyo_discovery_callback(conn: pyeiscp.Connection):
+        async def async_onkyo_discovery_callback(conn: pyeiscp.Connection) -> None:
             """Receiver discovered, connection not yet active."""
             info = ReceiverInfo(conn.host, conn.port, conn.name, conn.identifier)
             _LOGGER.debug("Receiver discovered: %s (%s)", info.model_name, info.host)
@@ -298,7 +298,7 @@ async def async_setup_platform(
         )
 
     @callback
-    def close_receiver(_event):
+    def close_receiver(_event: Event) -> None:
         for receiver in receivers.values():
             receiver.conn.close()
 
@@ -495,19 +495,23 @@ class OnkyoMediaPlayer(MediaPlayerEntity):
         self.async_write_ha_state()
 
     @callback
-    def _parse_source(self, source):
+    def _parse_source(self, source_raw: str | int | tuple[str]) -> None:
         # source is either a tuple of values or a single value,
         # so we convert to a tuple, when it is a single value.
-        if not isinstance(source, tuple):
-            source = (source,)
+        if isinstance(source_raw, str | int):
+            source = (str(source_raw),)
+        else:
+            source = source_raw
         for value in source:
             if value in self._source_mapping:
                 self._attr_source = self._source_mapping[value]
-                break
-            self._attr_source = "_".join(source)
+                return
+        self._attr_source = "_".join(source)
 
     @callback
-    def _parse_audio_information(self, audio_information):
+    def _parse_audio_information(
+        self, audio_information: tuple[str] | Literal["N/A"]
+    ) -> None:
         # If audio information is not available, N/A is returned,
         # so only update the audio information, when it is not N/A.
         if audio_information == "N/A":
@@ -523,7 +527,9 @@ class OnkyoMediaPlayer(MediaPlayerEntity):
         }
 
     @callback
-    def _parse_video_information(self, video_information):
+    def _parse_video_information(
+        self, video_information: tuple[str] | Literal["N/A"]
+    ) -> None:
         # If video information is not available, N/A is returned,
         # so only update the video information, when it is not N/A.
         if video_information == "N/A":
@@ -538,11 +544,11 @@ class OnkyoMediaPlayer(MediaPlayerEntity):
             if len(value) > 0
         }
 
-    def _query_av_info_delayed(self):
+    def _query_av_info_delayed(self) -> None:
         if self._zone == "main" and not self._query_timer:
 
             @callback
-            def _query_av_info():
+            def _query_av_info() -> None:
                 if self._supports_audio_info:
                     self._query_receiver("audio-information")
                 if self._supports_video_info:
diff --git a/mypy.ini b/mypy.ini
index 4ba1f41f4d4..b352d2747be 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -3166,6 +3166,16 @@ disallow_untyped_defs = true
 warn_return_any = true
 warn_unreachable = true
 
+[mypy-homeassistant.components.onkyo.*]
+check_untyped_defs = true
+disallow_incomplete_defs = true
+disallow_subclassing_any = true
+disallow_untyped_calls = true
+disallow_untyped_decorators = true
+disallow_untyped_defs = true
+warn_return_any = true
+warn_unreachable = true
+
 [mypy-homeassistant.components.open_meteo.*]
 check_untyped_defs = true
 disallow_incomplete_defs = true