diff --git a/app/lib/activitypub/activity/update.rb b/app/lib/activitypub/activity/update.rb
index 973706f5957..71b6ba5ca41 100644
--- a/app/lib/activitypub/activity/update.rb
+++ b/app/lib/activitypub/activity/update.rb
@@ -20,7 +20,7 @@ class ActivityPub::Activity::Update < ActivityPub::Activity
   def update_account
     return reject_payload! if @account.uri != object_uri
 
-    ActivityPub::ProcessAccountService.new.call(@account.username, @account.domain, @object, signed_with_known_key: true, request_id: @options[:request_id])
+    ActivityPub::ProcessAccountService.new.call(@account.username, @account.domain, @object, signed_with_known_key: true, request_id: @options[:request_id], allow_username_update: true)
   end
 
   def update_status
diff --git a/app/services/activitypub/process_account_service.rb b/app/services/activitypub/process_account_service.rb
index e5c23197284..de8c4a78ee0 100644
--- a/app/services/activitypub/process_account_service.rb
+++ b/app/services/activitypub/process_account_service.rb
@@ -27,7 +27,7 @@ class ActivityPub::ProcessAccountService < BaseService
     @options[:request_id] ||= "#{Time.now.utc.to_i}-#{username}@#{domain}"
 
     with_redis_lock("process_account:#{@uri}") do
-      @account            = Account.remote.find_by(uri: @uri) if @options[:only_key]
+      @account            = Account.remote.find_by(uri: @uri) if find_remote_account_by_uri?
       @account          ||= Account.find_remote(@username, @domain)
       @old_public_key     = @account&.public_key
       @old_protocol       = @account&.protocol
@@ -69,6 +69,10 @@ class ActivityPub::ProcessAccountService < BaseService
 
   private
 
+  def find_remote_account_by_uri?
+    @options[:only_key] || @options[:allow_username_update]
+  end
+
   def create_account
     @account = Account.new
     @account.protocol          = :activitypub
@@ -131,6 +135,7 @@ class ActivityPub::ProcessAccountService < BaseService
     @account.indexable               = @json['indexable'] || false
     @account.memorial                = @json['memorial'] || false
     @account.attribution_domains     = as_array(@json['attributionDomains'] || []).map { |item| value_or_id(item) }
+    @account.username                = @json['preferredUsername'] if @options[:allow_username_update]
   end
 
   def set_fetchable_key!
diff --git a/spec/requests/activitypub/inboxes_controller_spec.rb b/spec/requests/activitypub/inboxes_controller_spec.rb
index 4dbdea36c8b..94a0280c7d1 100644
--- a/spec/requests/activitypub/inboxes_controller_spec.rb
+++ b/spec/requests/activitypub/inboxes_controller_spec.rb
@@ -178,10 +178,10 @@ RSpec.describe ActivityPub::InboxesController, :sidekiq_inline do
         end.to(not_change { Account.count })
       end
 
-      it 'does not update the remote actors username' do
+      it 'updates the remote actors username' do
         post "/users/#{local_actor.username}/inbox", params: json.to_json, headers: headers
         expect(response).to have_http_status(202)
-        expect(remote_actor.reload.username).to eq(remote_actor_original_username)
+        expect(remote_actor.reload.username).to eq(remote_actor_new_username)
       end
     end
   end