diff --git a/lib/hooks/thread-hooks.js b/lib/hooks/thread-hooks.js
--- a/lib/hooks/thread-hooks.js
+++ b/lib/hooks/thread-hooks.js
@@ -19,6 +19,7 @@
 import {
   useUpdateFarcasterGroupNameAndDescription,
   useModifyFarcasterMembershipInput,
+  useAcceptInvite,
 } from '../shared/farcaster/farcaster-api.js';
 import {
   useFetchConversation,
@@ -505,6 +506,9 @@
     state => state.currentUserInfo && state.currentUserInfo.id,
   );
   const keyserverCall = useJoinKeyserverThread();
+  const farcasterAcceptInvite = useAcceptInvite();
+  const refreshFarcasterConversation = useRefreshFarcasterConversation();
+
   return React.useCallback(
     async (input: UseJoinThreadInput) =>
       threadSpecs[input.rawThreadInfo.type].protocol().joinThread(
@@ -516,9 +520,17 @@
           processAndSendDMOperation,
           keyserverJoinThread: keyserverCall,
           calendarQuery: input.calendarQuery,
+          farcasterAcceptInvite,
+          refreshFarcasterConversation,
         },
       ),
-    [keyserverCall, processAndSendDMOperation, viewerID],
+    [
+      farcasterAcceptInvite,
+      keyserverCall,
+      processAndSendDMOperation,
+      refreshFarcasterConversation,
+      viewerID,
+    ],
   );
 }
 
diff --git a/lib/shared/farcaster/farcaster-api.js b/lib/shared/farcaster/farcaster-api.js
--- a/lib/shared/farcaster/farcaster-api.js
+++ b/lib/shared/farcaster/farcaster-api.js
@@ -568,6 +568,25 @@
   );
 }
 
+export type AcceptInviteInput = {
+  +conversationId: string,
+};
+
+function useAcceptInvite(): (input: AcceptInviteInput) => Promise<void> {
+  const { sendFarcasterRequest } = useTunnelbroker();
+  return React.useCallback(
+    async (input: AcceptInviteInput) => {
+      await sendFarcasterRequest({
+        apiVersion: 'v2',
+        endpoint: 'direct-cast-accept-group-invite',
+        method: { type: 'POST' },
+        payload: JSON.stringify(input),
+      });
+    },
+    [sendFarcasterRequest],
+  );
+}
+
 export {
   useSendFarcasterTextMessage,
   useFetchFarcasterMessages,
@@ -581,4 +600,5 @@
   useGetFarcasterDirectCastUsers,
   useModifyFarcasterMembershipInput,
   useSendFarcasterReaction,
+  useAcceptInvite,
 };
diff --git a/lib/shared/threads/protocols/farcaster-thread-protocol.js b/lib/shared/threads/protocols/farcaster-thread-protocol.js
--- a/lib/shared/threads/protocols/farcaster-thread-protocol.js
+++ b/lib/shared/threads/protocols/farcaster-thread-protocol.js
@@ -106,6 +106,8 @@
   SendMultimediaMessageUtils,
   ProtocolSendReactionInput,
   SendReactionUtils,
+  JoinThreadUtils,
+  ProtocolJoinThreadInput,
 } from '../thread-spec.js';
 import { threadTypeIsPersonal } from '../thread-specs.js';
 
@@ -905,8 +907,24 @@
     throw new Error('deleteMessage method is not yet implemented');
   },
 
-  joinThread: async (): Promise<ThreadJoinPayload> => {
-    throw new Error('joinThread method is not yet implemented');
+  joinThread: async (
+    input: ProtocolJoinThreadInput,
+    utils: JoinThreadUtils,
+  ): Promise<ThreadJoinPayload> => {
+    const threadID = input.rawThreadInfo.id;
+    const conversationID = conversationIDFromFarcasterThreadID(threadID);
+    await utils.farcasterAcceptInvite({
+      conversationId: conversationID,
+    });
+
+    await utils.refreshFarcasterConversation(conversationID);
+
+    return ({
+      updatesResult: { newUpdates: [] },
+      rawMessageInfos: [],
+      truncationStatuses: {},
+      userInfos: [],
+    }: ThreadJoinPayload);
   },
 
   onOpenThread: (
diff --git a/lib/shared/threads/thread-spec.js b/lib/shared/threads/thread-spec.js
--- a/lib/shared/threads/thread-spec.js
+++ b/lib/shared/threads/thread-spec.js
@@ -100,6 +100,7 @@
   CreateFarcasterGroupInput,
   ModifyFarcasterMembershipInput,
   SendReactionInput,
+  AcceptInviteInput,
 } from '../farcaster/farcaster-api.js';
 import type { FarcasterConversation } from '../farcaster/farcaster-conversation-types.js';
 import type { FarcasterMessageFetchingContextType } from '../farcaster/farcaster-message-fetching-context.js';
@@ -374,6 +375,8 @@
   +processAndSendDMOperation: OutboundDMOperationSpecification => Promise<void>,
   +keyserverJoinThread: ClientThreadJoinRequest => Promise<ThreadJoinPayload>,
   +calendarQuery: () => CalendarQuery,
+  +farcasterAcceptInvite: (input: AcceptInviteInput) => Promise<void>,
+  +refreshFarcasterConversation: (conversationId: string) => Promise<mixed>,
 };
 
 export type ProtocolOnOpenThreadInput = {