diff --git a/homeassistant/components/tts/__init__.py b/homeassistant/components/tts/__init__.py
index 45db6007e31..4628ec8768a 100644
--- a/homeassistant/components/tts/__init__.py
+++ b/homeassistant/components/tts/__init__.py
@@ -203,55 +203,28 @@ async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
             language = service.data.get(ATTR_LANGUAGE)
             options = service.data.get(ATTR_OPTIONS)
 
-            if tts.base_url is None or tts.base_url == get_url(hass):
-                tts.process_options(p_type, language, options)
-                params = {
-                    "message": message,
-                }
-                if cache is not None:
-                    params["cache"] = "true" if cache else "false"
-                if language is not None:
-                    params["language"] = language
-                if options is not None:
-                    params.update(options)
-
-                await hass.services.async_call(
-                    DOMAIN_MP,
-                    SERVICE_PLAY_MEDIA,
-                    {
-                        ATTR_ENTITY_ID: entity_ids,
-                        ATTR_MEDIA_CONTENT_ID: generate_media_source_id(
-                            DOMAIN,
-                            str(yarl.URL.build(path=p_type, query=params)),
-                        ),
-                        ATTR_MEDIA_CONTENT_TYPE: MEDIA_TYPE_MUSIC,
-                    },
-                    blocking=True,
-                    context=service.context,
-                )
-                return
-
-            try:
-                url = await tts.async_get_url_path(
-                    p_type, message, cache=cache, language=language, options=options
-                )
-            except HomeAssistantError as err:
-                _LOGGER.error("Error on init TTS: %s", err)
-                return
-
-            base = tts.base_url or get_url(hass)
-            url = base + url
-
-            data = {
-                ATTR_MEDIA_CONTENT_ID: url,
-                ATTR_MEDIA_CONTENT_TYPE: MEDIA_TYPE_MUSIC,
-                ATTR_ENTITY_ID: entity_ids,
+            tts.process_options(p_type, language, options)
+            params = {
+                "message": message,
             }
+            if cache is not None:
+                params["cache"] = "true" if cache else "false"
+            if language is not None:
+                params["language"] = language
+            if options is not None:
+                params.update(options)
 
             await hass.services.async_call(
                 DOMAIN_MP,
                 SERVICE_PLAY_MEDIA,
-                data,
+                {
+                    ATTR_ENTITY_ID: entity_ids,
+                    ATTR_MEDIA_CONTENT_ID: generate_media_source_id(
+                        DOMAIN,
+                        str(yarl.URL.build(path=p_type, query=params)),
+                    ),
+                    ATTR_MEDIA_CONTENT_TYPE: MEDIA_TYPE_MUSIC,
+                },
                 blocking=True,
                 context=service.context,
             )
diff --git a/homeassistant/components/tts/media_source.py b/homeassistant/components/tts/media_source.py
index b212fc9ec3a..99ef3dd85a0 100644
--- a/homeassistant/components/tts/media_source.py
+++ b/homeassistant/components/tts/media_source.py
@@ -17,6 +17,7 @@ from homeassistant.components.media_source.models import (
 )
 from homeassistant.core import HomeAssistant, callback
 from homeassistant.exceptions import HomeAssistantError
+from homeassistant.helpers.network import get_url
 
 from .const import DOMAIN
 
@@ -64,6 +65,9 @@ class TTSMediaSource(MediaSource):
 
         mime_type = mimetypes.guess_type(url)[0] or "audio/mpeg"
 
+        if manager.base_url and manager.base_url != get_url(self.hass):
+            url = f"{manager.base_url}{url}"
+
         return PlayMedia(url, mime_type)
 
     async def async_browse_media(
diff --git a/tests/components/tts/test_init.py b/tests/components/tts/test_init.py
index 098dde91cfa..7fd8cc0facb 100644
--- a/tests/components/tts/test_init.py
+++ b/tests/components/tts/test_init.py
@@ -366,7 +366,8 @@ async def test_setup_component_and_test_service_with_base_url_set(hass):
     assert len(calls) == 1
     assert calls[0].data[ATTR_MEDIA_CONTENT_TYPE] == MEDIA_TYPE_MUSIC
     assert (
-        calls[0].data[ATTR_MEDIA_CONTENT_ID] == "http://fnord"
+        await get_media_source_url(hass, calls[0].data[ATTR_MEDIA_CONTENT_ID])
+        == "http://fnord"
         "/api/tts_proxy/42f18378fd4393d18c8dd11d03fa9563c1e54491"
         "_en_-_demo.mp3"
     )