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
@@ -568,6 +568,8 @@
   );
   const keyserverLeaveThread = useKeyserverCall(leaveThread);
   const dispatchActionPromise = useDispatchActionPromise();
+  const modifyFarcasterMembership = useModifyFarcasterMembershipInput();
+  const auxUserStore = useSelector(state => state.auxUserStore);
 
   return React.useCallback(
     (input: UseLeaveThreadInput) =>
@@ -577,11 +579,15 @@
           processAndSendDMOperation,
           keyserverLeaveThread,
           dispatchActionPromise,
+          modifyFarcasterMembership,
+          auxUserStore,
         },
       ),
     [
+      auxUserStore,
       dispatchActionPromise,
       keyserverLeaveThread,
+      modifyFarcasterMembership,
       processAndSendDMOperation,
       viewerID,
     ],
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
@@ -5,8 +5,10 @@
 import { fetchMessagesBeforeCursorActionTypes } from '../../../actions/message-actions.js';
 import {
   changeThreadMemberRolesActionTypes,
+  leaveThreadActionTypes,
   removeUsersFromThreadActionTypes,
 } from '../../../actions/thread-action-types.js';
+import type { LeaveThreadResult } from '../../../hooks/thread-hooks.js';
 import { getFarcasterRolePermissionsBlobs } from '../../../permissions/farcaster-permissions.js';
 import type { RolePermissionBlobs } from '../../../permissions/thread-permissions.js';
 import type { SetThreadUnreadStatusPayload } from '../../../types/activity-types.js';
@@ -85,6 +87,8 @@
   ChangeThreadMemberRolesUtils,
   ProtocolRemoveUsersFromThreadInput,
   RemoveUsersFromThreadUtils,
+  ProtocolLeaveThreadInput,
+  LeaveThreadUtils,
 } from '../thread-spec.js';
 
 const farcasterThreadProtocol: ThreadProtocol<MemberInfoSansPermissions> = {
@@ -430,8 +434,57 @@
     };
   },
 
-  leaveThread: async () => {
-    throw new Error('leaveThread method is not yet implemented');
+  leaveThread: async (
+    input: ProtocolLeaveThreadInput,
+    utils: LeaveThreadUtils,
+  ): Promise<LeaveThreadResult> => {
+    const { threadInfo, viewerID } = input;
+    const { modifyFarcasterMembership, dispatchActionPromise, auxUserStore } =
+      utils;
+
+    const conversationId = conversationIDFromFarcasterThreadID(threadInfo.id);
+
+    const promise = (async () => {
+      if (viewerID) {
+        const viewerFID =
+          auxUserStore.auxUserInfos[viewerID]?.fid ??
+          extractFIDFromUserID(viewerID);
+
+        if (viewerFID) {
+          const modifyFarcasterMembershipInput: ModifyFarcasterMembershipInput =
+            {
+              conversationId,
+              action: 'remove',
+              targetFid: parseInt(viewerFID, 10),
+            };
+
+          await modifyFarcasterMembership(modifyFarcasterMembershipInput);
+        }
+      }
+
+      return {
+        updatesResult: {
+          newUpdates: [
+            {
+              type: updateTypes.DELETE_THREAD,
+              threadID: threadInfo.id,
+              id: threadInfo.id,
+              time: Date.now(),
+            },
+          ],
+        },
+      };
+    })();
+
+    const customKeyName = `${leaveThreadActionTypes.started}:${threadInfo.id}`;
+    void dispatchActionPromise(leaveThreadActionTypes, promise, {
+      customKeyName,
+    });
+    await promise;
+
+    return {
+      invalidatedThreads: [threadInfo.id],
+    };
   },
 
   convertClientDBThreadInfo: (
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
@@ -288,6 +288,10 @@
   +processAndSendDMOperation: OutboundDMOperationSpecification => Promise<void>,
   +keyserverLeaveThread: LeaveThreadInput => Promise<LeaveThreadPayload>,
   +dispatchActionPromise: DispatchActionPromise,
+  +modifyFarcasterMembership: (
+    input: ModifyFarcasterMembershipInput,
+  ) => Promise<void>,
+  +auxUserStore: AuxUserStore,
 };
 
 export type ProtocolFetchMessageInput = {