diff --git a/docs/en/tutorial/routers.md b/docs/en/tutorial/routers.md
index e9c478c..67c16d8 100644
--- a/docs/en/tutorial/routers.md
+++ b/docs/en/tutorial/routers.md
@@ -182,7 +182,7 @@ from fasthttp import FastHTTP
 
 from src.clients.integrations import setup_integrations_router
 
-app = FastHTTP()
+app = FastHTTP(base_url="https://api.example.com")
 app.include_router(setup_integrations_router())
 ```
 
diff --git a/docs/ru/tutorial/routers.md b/docs/ru/tutorial/routers.md
index 53f3676..e5bde6e 100644
--- a/docs/ru/tutorial/routers.md
+++ b/docs/ru/tutorial/routers.md
@@ -186,7 +186,7 @@ from fasthttp import FastHTTP
 
 from src.clients.integrations import setup_integrations_router
 
-app = FastHTTP()
+app = FastHTTP(base_url="https://api.example.com")
 app.include_router(setup_integrations_router())
 ```
 
diff --git a/fasthttp/app.py b/fasthttp/app.py
index 7050798..9082e42 100644
--- a/fasthttp/app.py
+++ b/fasthttp/app.py
@@ -278,6 +278,23 @@ async def lifespan(app: FastHTTP):
             ),
         ] = "v4",
         base_url: Annotated[
+            str | None,
+            Doc(
+                """
+                Default base URL for included routers with relative paths.
+
+                This value is used by `include_router()` when the router tree
+                contains relative URLs like `/users` and no explicit
+                `base_url` override is provided.
+
+                Example:
+                ```python
+                app = FastHTTP(base_url="https://api.example.com")
+                ```
+                """
+            ),
+        ] = None,
+        docs_base_url: Annotated[
             str,
             Doc(
                 """
@@ -288,7 +305,7 @@ async def lifespan(app: FastHTTP):
 
                 Example:
                 ```python
-                app = FastHTTP(base_url="/api")
+                app = FastHTTP(docs_base_url="/api")
                 ```
                 """
             ),
@@ -300,6 +317,7 @@ async def lifespan(app: FastHTTP):
         self.lifespan = lifespan
         self.proxy = proxy
         self.base_url = base_url
+        self.docs_base_url = docs_base_url
         self.generate_startup_uuid = generate_startup_uuid
         self.startup_uuid_version = startup_uuid_version
 
@@ -550,9 +568,11 @@ def include_router(
             tags: Tags prepended before router tags.
             dependencies: Dependencies prepended before router dependencies.
             base_url: Base URL override for the included router tree.
+                If not provided, `FastHTTP.base_url` will be used.
         """
+        resolved_base_url = base_url if base_url is not None else self.base_url
         routes = router.build_routes(
-            base_url=base_url,
+            base_url=resolved_base_url,
             prefix=prefix,
             tags=tags,
             dependencies=dependencies,
@@ -1028,17 +1048,17 @@ async def index(resp):
             host: Host to bind to. Default is "127.0.0.1".
             port: Port to bind to. Default is 8000.
             base_url: Optional prefix for documentation endpoints.
-                If not provided, `FastHTTP.base_url` will be used.
+                If not provided, `FastHTTP.docs_base_url` will be used.
         """
         self.logger.info("FastHTTP started")
 
-        base_url = (
-            base_url if base_url is not None else self.base_url
+        docs_base_url = (
+            base_url if base_url is not None else self.docs_base_url
         )
-        app = ASGIApp(self, base_url=base_url)
+        app = ASGIApp(self, base_url=docs_base_url)
 
         server_base_url = f"http://{host}:{port}"
-        docs_urls = build_docs_urls(base_url)
+        docs_urls = build_docs_urls(docs_base_url)
 
         print(f"\n\033[92mfasthttp\033[0m running on \033[94m{server_base_url}\033[0m")
         print(
diff --git a/tests/test_app.py b/tests/test_app.py
index acdf55d..8583d3a 100644
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -34,11 +34,17 @@ def test_app_creation_with_all_parameters(self) -> None:
         assert app.request_configs["GET"]["timeout"] == 60.0
         assert app.request_configs["POST"]["timeout"] == 120.0
 
-    def test_app_creation_with_docs_base_url(self) -> None:
+    def test_app_creation_with_base_url(self) -> None:
         """Test FastHTTP creation with base_url."""
-        app = FastHTTP(base_url="/api")
+        app = FastHTTP(base_url="https://example.com")
+
+        assert app.base_url == "https://example.com"
+
+    def test_app_creation_with_docs_base_url(self) -> None:
+        """Test FastHTTP creation with docs_base_url."""
+        app = FastHTTP(docs_base_url="/api")
 
-        assert app.base_url == "/api"
+        assert app.docs_base_url == "/api"
 
     def test_app_get_decorator(self) -> None:
         """Test GET decorator registers route."""
@@ -170,13 +176,26 @@ async def handler(resp: Response) -> dict:
         with pytest.raises(ValueError, match="Relative URL requires base_url"):
             app.include_router(router)
 
+    def test_app_include_router_uses_app_base_url_by_default(self) -> None:
+        app = FastHTTP(base_url="https://example.com")
+        router = Router(prefix="/v1")
+
+        @router.get("/me")
+        async def handler(resp: Response) -> dict:
+            return resp.json()
+
+        app.include_router(router)
+
+        assert len(app.routes) == 1
+        assert app.routes[0].url == "https://example.com/v1/me"
+
     @pytest.mark.asyncio
     async def test_asgi_handle_request_docs_uses_app_docs_base_url(self) -> None:
-        """Test ASGI docs path uses base_url from FastHTTP."""
+        """Test ASGI docs path uses docs_base_url from FastHTTP."""
         from fasthttp.app import ASGIApp
 
-        app = FastHTTP(base_url="/api")
-        asgi_app = ASGIApp(app, base_url=app.base_url)
+        app = FastHTTP(docs_base_url="/api")
+        asgi_app = ASGIApp(app, base_url=app.docs_base_url)
 
         scope = {"type": "http", "path": "/api/docs", "method": "GET"}
         receive = AsyncMock()