diff --git a/CHANGES/1147.feature b/CHANGES/1147.feature
new file mode 100644
index 00000000..fa34e703
--- /dev/null
+++ b/CHANGES/1147.feature
@@ -0,0 +1 @@
+If router does not support custom event it does not break and passes it to included routers
\ No newline at end of file
diff --git a/aiogram/dispatcher/event/telegram.py b/aiogram/dispatcher/event/telegram.py
index bb943004..a468816c 100644
--- a/aiogram/dispatcher/event/telegram.py
+++ b/aiogram/dispatcher/event/telegram.py
@@ -49,8 +49,9 @@ class TelegramEventObserver:
     def _resolve_middlewares(self) -> List[MiddlewareType[TelegramObject]]:
         middlewares: List[MiddlewareType[TelegramObject]] = []
         for router in reversed(tuple(self.router.chain_head)):
-            observer = router.observers[self.event_name]
-            middlewares.extend(observer.middleware)
+            observer = router.observers.get(self.event_name)
+            if observer:
+                middlewares.extend(observer.middleware)
 
         return middlewares
 
diff --git a/aiogram/dispatcher/router.py b/aiogram/dispatcher/router.py
index 86359ce0..85c41ae8 100644
--- a/aiogram/dispatcher/router.py
+++ b/aiogram/dispatcher/router.py
@@ -105,27 +105,31 @@ class Router:
 
     async def propagate_event(self, update_type: str, event: TelegramObject, **kwargs: Any) -> Any:
         kwargs.update(event_router=self)
-        observer = self.observers[update_type]
+        observer = self.observers.get(update_type)
 
         async def _wrapped(telegram_event: TelegramObject, **data: Any) -> Any:
             return await self._propagate_event(
                 observer=observer, update_type=update_type, event=telegram_event, **data
             )
 
-        return await observer.wrap_outer_middleware(_wrapped, event=event, data=kwargs)
+        if observer:
+            return await observer.wrap_outer_middleware(_wrapped, event=event, data=kwargs)
+        return await _wrapped(event, **kwargs)
 
     async def _propagate_event(
         self,
-        observer: TelegramEventObserver,
+        observer: Optional[TelegramEventObserver],
         update_type: str,
         event: TelegramObject,
         **kwargs: Any,
     ) -> Any:
-        response = await observer.trigger(event, **kwargs)
-        if response is REJECTED:
-            return UNHANDLED
-        if response is not UNHANDLED:
-            return response
+        response = UNHANDLED
+        if observer:
+            response = await observer.trigger(event, **kwargs)
+            if response is REJECTED:
+                return UNHANDLED
+            if response is not UNHANDLED:
+                return response
 
         for router in self.sub_routers:
             response = await router.propagate_event(update_type=update_type, event=event, **kwargs)
diff --git a/tests/test_dispatcher/test_router.py b/tests/test_dispatcher/test_router.py
index 3404822d..1ac78480 100644
--- a/tests/test_dispatcher/test_router.py
+++ b/tests/test_dispatcher/test_router.py
@@ -1,6 +1,7 @@
 import pytest
 
 from aiogram.dispatcher.event.bases import UNHANDLED, SkipHandler, skip
+from aiogram.dispatcher.event.telegram import TelegramEventObserver
 from aiogram.dispatcher.router import Router
 
 
@@ -161,3 +162,20 @@ class TestRouter:
         assert tuple(r2_1.chain_head) == (r2_1, r1)
         assert tuple(r2_2.chain_head) == (r2_2, r1)
         assert tuple(r3.chain_head) == (r3, r2_1, r1)
+
+    async def test_custom_evenv_nested_router(self):
+        r1 = Router()
+        r2 = Router()
+        r3 = Router()
+        r3.observers["custom-event"] = TelegramEventObserver(r3, event_name="custom-event")
+
+        async def handler(evt):
+            return evt
+
+        r1.include_router(r2)
+        r1.include_router(r3)
+        r3.observers["custom-event"].register(handler)
+
+        assert await r1.propagate_event(update_type="custom-event", event=None) is None
+        assert await r2.propagate_event(update_type="custom-event", event=None) is UNHANDLED
+        assert await r3.propagate_event(update_type="custom-event", event=None) is None