diff --git a/src/Discord.Net.WebSocket/BaseSocketClient.Events.cs b/src/Discord.Net.WebSocket/BaseSocketClient.Events.cs
index 1cd35768d..fe13d327e 100644
--- a/src/Discord.Net.WebSocket/BaseSocketClient.Events.cs
+++ b/src/Discord.Net.WebSocket/BaseSocketClient.Events.cs
@@ -603,13 +603,13 @@ namespace Discord.WebSocket
         /// <summary>
         ///     Fired when a thread is updated within a guild.
         /// </summary>
-        public event Func<SocketThreadChannel, SocketThreadChannel, Task> ThreadUpdated
+        public event Func<Cacheable<SocketThreadChannel, ulong>, SocketThreadChannel, Task> ThreadUpdated
         {
             add { _threadUpdated.Add(value); }
             remove { _threadUpdated.Remove(value); }
         }
 
-        internal readonly AsyncEvent<Func<SocketThreadChannel, SocketThreadChannel, Task>> _threadUpdated = new AsyncEvent<Func<SocketThreadChannel, SocketThreadChannel, Task>>();
+        internal readonly AsyncEvent<Func<Cacheable<SocketThreadChannel, ulong>, SocketThreadChannel, Task>> _threadUpdated = new();
 
         /// <summary>
         ///     Fired when a thread is deleted.
diff --git a/src/Discord.Net.WebSocket/DiscordSocketClient.cs b/src/Discord.Net.WebSocket/DiscordSocketClient.cs
index b79eeb099..007e9f68a 100644
--- a/src/Discord.Net.WebSocket/DiscordSocketClient.cs
+++ b/src/Discord.Net.WebSocket/DiscordSocketClient.cs
@@ -2243,16 +2243,25 @@ namespace Discord.WebSocket
                                         return;
                                     }
 
-                                    var channel = (SocketThreadChannel)guild.GetChannel(data.Id);
+                                    var threadChannel = guild.ThreadChannels.FirstOrDefault(x => x.Id == data.Id);
+                                    var before = threadChannel != null
+                                        ? new Cacheable<SocketThreadChannel, ulong>(threadChannel.Clone(), data.Id, true, () => Task.FromResult((SocketThreadChannel)null))
+                                        : new Cacheable<SocketThreadChannel, ulong>(null, data.Id, false, () => Task.FromResult((SocketThreadChannel)null));
 
-                                    if (channel == null)
+                                    if (threadChannel != null)
                                     {
-                                        await UnknownChannelAsync(type, data.Id);
-                                        return;
-                                    }
+                                        threadChannel.Update(State, data);
 
-                                    var before = channel.Clone();
-                                    channel.Update(State, data);
+                                        if (data.ThreadMember.IsSpecified)
+                                            threadChannel.AddOrUpdateThreadMember(data.ThreadMember.Value, guild.CurrentUser);
+                                    }
+                                    else
+                                    {
+                                        // Thread is updated but was not cached, likely meaning the thread was unarchived.
+                                        threadChannel = (SocketThreadChannel)guild.AddChannel(State, data);
+                                        if (data.ThreadMember.IsSpecified)
+                                            threadChannel.AddOrUpdateThreadMember(data.ThreadMember.Value, guild.CurrentUser);
+                                    }
 
                                     if (!(guild?.IsSynced ?? true))
                                     {
@@ -2260,7 +2269,7 @@ namespace Discord.WebSocket
                                         return;
                                     }
 
-                                    await TimedInvokeAsync(_threadUpdated, nameof(ThreadUpdated), before, channel).ConfigureAwait(false);
+                                    await TimedInvokeAsync(_threadUpdated, nameof(ThreadUpdated), before, threadChannel).ConfigureAwait(false);
                                 }
                                 break;
                             case "THREAD_DELETE":