diff --git a/native/components/auto-join-community-handler.react.js b/native/components/auto-join-community-handler.react.js
new file mode 100644
--- /dev/null
+++ b/native/components/auto-join-community-handler.react.js
@@ -0,0 +1,143 @@
+// @flow
+
+import * as React from 'react';
+
+import {
+  joinThreadActionTypes,
+  useJoinThread,
+} from 'lib/actions/thread-actions.js';
+import { NeynarClientContext } from 'lib/components/neynar-client-provider.react.js';
+import blobService from 'lib/facts/blob-service.js';
+import { cookieSelector } from 'lib/selectors/keyserver-selectors.js';
+import { farcasterChannelTagBlobHash } from 'lib/shared/community-utils.js';
+import { authoritativeKeyserverID } from 'lib/utils/authoritative-keyserver.js';
+import { getBlobFetchableURL } from 'lib/utils/blob-service.js';
+import { useCurrentUserFID } from 'lib/utils/farcaster-utils.js';
+import { useDispatchActionPromise } from 'lib/utils/redux-promise-utils.js';
+
+import { nonThreadCalendarQuery } from '../navigation/nav-selectors.js';
+import { NavContext } from '../navigation/navigation-context.js';
+import { useSelector } from '../redux/redux-utils.js';
+
+function AutoJoinCommunityHandler(): React.Node {
+  const isActive = useSelector(state => state.lifecycleState !== 'background');
+
+  const cookie = useSelector(cookieSelector(authoritativeKeyserverID()));
+  const hasUserCookie = !!(cookie && cookie.startsWith('user='));
+  const currentUserID = useSelector(state => state.currentUserInfo?.id);
+  const loggedIn = !!currentUserID && hasUserCookie;
+
+  const fid = useCurrentUserFID();
+
+  const neynarClient = React.useContext(NeynarClientContext)?.client;
+
+  const navContext = React.useContext(NavContext);
+
+  const calendarQuery = useSelector(state =>
+    nonThreadCalendarQuery({
+      redux: state,
+      navContext,
+    }),
+  );
+
+  const joinThread = useJoinThread();
+
+  const joinThreadActionPromise = React.useCallback(
+    async (communityID: string, channelID: string) => {
+      const query = calendarQuery();
+
+      return await joinThread({
+        threadID: communityID,
+        calendarQuery: {
+          startDate: query.startDate,
+          endDate: query.endDate,
+          filters: [
+            ...query.filters,
+            { type: 'threads', threadIDs: [communityID] },
+          ],
+        },
+        farcasterChannelID: channelID,
+      });
+    },
+    [calendarQuery, joinThread],
+  );
+
+  const dispatchActionPromise = useDispatchActionPromise();
+
+  const threadInfos = useSelector(state => state.threadStore.threadInfos);
+
+  React.useEffect(() => {
+    if (!loggedIn || !isActive || !fid || !neynarClient) {
+      return;
+    }
+
+    void (async () => {
+      const followedFarcasterChannels =
+        await neynarClient.fetchFollowedFarcasterChannels(fid);
+
+      const followedFarcasterChannelIDs = followedFarcasterChannels.map(
+        channel => channel.id,
+      );
+
+      const fetchBlobPromises = followedFarcasterChannelIDs.map(channelID => {
+        const blobHash = farcasterChannelTagBlobHash(
+          channelID,
+          authoritativeKeyserverID(),
+        );
+        const blobURL = getBlobFetchableURL(blobHash);
+
+        return fetch(blobURL, {
+          method: blobService.httpEndpoints.GET_BLOB.method,
+        });
+      });
+
+      const fetchBlobResults = await Promise.all(fetchBlobPromises);
+
+      const farcasterChannelTagBlobsPromises = fetchBlobResults
+        .map(blobResult => {
+          if (blobResult.status !== 200) {
+            return null;
+          }
+
+          return blobResult.json();
+        })
+        .filter(Boolean);
+
+      const farcasterChannelTagBlobs: $ReadOnlyArray<{
+        +commCommunityID: string,
+        +farcasterChannelID: string,
+      }> = await Promise.all(farcasterChannelTagBlobsPromises);
+
+      const joinThreadPromises = farcasterChannelTagBlobs
+        .map(blob => {
+          const threadID = `${authoritativeKeyserverID()}|${
+            blob.commCommunityID
+          }`;
+
+          if (threadInfos[threadID]) {
+            return null;
+          }
+
+          return dispatchActionPromise(
+            joinThreadActionTypes,
+            joinThreadActionPromise(threadID, blob.farcasterChannelID),
+          );
+        })
+        .filter(Boolean);
+
+      await Promise.all(joinThreadPromises);
+    })();
+  }, [
+    threadInfos,
+    dispatchActionPromise,
+    fid,
+    isActive,
+    joinThreadActionPromise,
+    loggedIn,
+    neynarClient,
+  ]);
+
+  return null;
+}
+
+export { AutoJoinCommunityHandler };
diff --git a/native/root.react.js b/native/root.react.js
--- a/native/root.react.js
+++ b/native/root.react.js
@@ -46,6 +46,7 @@
 import ChatContextProvider from './chat/chat-context-provider.react.js';
 import MessageEditingContextProvider from './chat/message-editing-context-provider.react.js';
 import AccessTokenHandler from './components/access-token-handler.react.js';
+import { AutoJoinCommunityHandler } from './components/auto-join-community-handler.react.js';
 import ConnectFarcasterAlertHandler from './components/connect-farcaster-alert-handler.react.js';
 import { FeatureFlagsProvider } from './components/feature-flags-provider.react.js';
 import PersistedStateGate from './components/persisted-state-gate.js';
@@ -340,6 +341,7 @@
                                                 <PrekeysHandler />
                                                 <ReportHandler />
                                                 <FarcasterDataHandler />
+                                                <AutoJoinCommunityHandler />
                                               </PersistedStateGate>
                                               {navigation}
                                             </RegistrationContextProvider>