diff --git a/plugins/chat/app/models/chat/thread.rb b/plugins/chat/app/models/chat/thread.rb
index f78fc05f02e..6b1eafedaea 100644
--- a/plugins/chat/app/models/chat/thread.rb
+++ b/plugins/chat/app/models/chat/thread.rb
@@ -34,6 +34,21 @@ module Chat
       original_message.excerpt(max_length: EXCERPT_LENGTH)
     end
 
+    def self.grouped_messages(thread_ids: nil, message_ids: nil, include_original_message: true)
+      DB.query(<<~SQL, message_ids: message_ids, thread_ids: thread_ids)
+        SELECT thread_id,
+          array_agg(chat_messages.id ORDER BY chat_messages.created_at, chat_messages.id) AS thread_message_ids,
+          chat_threads.original_message_id
+        FROM chat_messages
+        INNER JOIN chat_threads ON chat_threads.id = chat_messages.thread_id
+        WHERE thread_id IS NOT NULL
+        #{thread_ids ? "AND thread_id IN (:thread_ids)" : ""}
+        #{message_ids ? "AND chat_messages.id IN (:message_ids)" : ""}
+        #{include_original_message ? "" : "AND chat_messages.id != chat_threads.original_message_id"}
+        GROUP BY thread_id, chat_threads.original_message_id;
+      SQL
+    end
+
     def self.ensure_consistency!
       update_counts
     end
diff --git a/plugins/chat/app/services/chat/publisher.rb b/plugins/chat/app/services/chat/publisher.rb
index 81e3fd4c736..6b847234dd3 100644
--- a/plugins/chat/app/services/chat/publisher.rb
+++ b/plugins/chat/app/services/chat/publisher.rb
@@ -167,11 +167,31 @@ module Chat
     end
 
     def self.publish_bulk_delete!(chat_channel, deleted_message_ids)
-      # TODO (martin) Handle sending this through for all the threads that
-      # may contain the deleted messages as well.
+      Chat::Thread
+        .grouped_messages(message_ids: deleted_message_ids)
+        .each do |group|
+          MessageBus.publish(
+            thread_message_bus_channel(chat_channel.id, group.thread_id),
+            {
+              type: "bulk_delete",
+              deleted_ids: group.thread_message_ids,
+              deleted_at: Time.zone.now,
+            },
+            permissions(chat_channel),
+          )
+
+          # Don't need to publish to the main channel if the messages deleted
+          # were a part of the thread (except the original message ID, since
+          # that shows in the main channel).
+          deleted_message_ids =
+            deleted_message_ids - (group.thread_message_ids - [group.original_message_id])
+        end
+
+      return if deleted_message_ids.empty?
+
       MessageBus.publish(
         root_message_bus_channel(chat_channel.id),
-        { typ: "bulk_delete", deleted_ids: deleted_message_ids, deleted_at: Time.zone.now },
+        { type: "bulk_delete", deleted_ids: deleted_message_ids, deleted_at: Time.zone.now },
         permissions(chat_channel),
       )
     end
diff --git a/plugins/chat/assets/javascripts/discourse/services/chat-channel-pane-subscriptions-manager.js b/plugins/chat/assets/javascripts/discourse/services/chat-channel-pane-subscriptions-manager.js
index 30d4aec8de3..e8d1080baa5 100644
--- a/plugins/chat/assets/javascripts/discourse/services/chat-channel-pane-subscriptions-manager.js
+++ b/plugins/chat/assets/javascripts/discourse/services/chat-channel-pane-subscriptions-manager.js
@@ -26,15 +26,6 @@ export default class ChatChannelPaneSubscriptionsManager extends ChatPaneBaseSub
     return;
   }
 
-  handleBulkDeleteMessage(data) {
-    data.deleted_ids.forEach((deletedId) => {
-      this.handleDeleteMessage({
-        deleted_id: deletedId,
-        deleted_at: data.deleted_at,
-      });
-    });
-  }
-
   handleThreadCreated(data) {
     const message = this.messagesManager.findMessage(data.chat_message.id);
     if (message) {
diff --git a/plugins/chat/assets/javascripts/discourse/services/chat-channel-thread-pane-subscriptions-manager.js b/plugins/chat/assets/javascripts/discourse/services/chat-channel-thread-pane-subscriptions-manager.js
index a3e897b028f..bee7089edc2 100644
--- a/plugins/chat/assets/javascripts/discourse/services/chat-channel-thread-pane-subscriptions-manager.js
+++ b/plugins/chat/assets/javascripts/discourse/services/chat-channel-thread-pane-subscriptions-manager.js
@@ -39,11 +39,6 @@ export default class ChatChannelThreadPaneSubscriptionsManager extends ChatPaneB
     return;
   }
 
-  // TODO (martin) Hook this up correctly in Chat::Publisher for threads.
-  handleBulkDeleteMessage() {
-    return;
-  }
-
   // NOTE: noop for now, later we may want to do scrolling or something like
   // we do in the channel pane.
   afterProcessedMessage() {
diff --git a/plugins/chat/assets/javascripts/discourse/services/chat-pane-base-subscriptions-manager.js b/plugins/chat/assets/javascripts/discourse/services/chat-pane-base-subscriptions-manager.js
index 3a09348d6a0..d02962207fb 100644
--- a/plugins/chat/assets/javascripts/discourse/services/chat-pane-base-subscriptions-manager.js
+++ b/plugins/chat/assets/javascripts/discourse/services/chat-pane-base-subscriptions-manager.js
@@ -177,8 +177,13 @@ export default class ChatPaneBaseSubscriptionsManager extends Service {
     }
   }
 
-  handleBulkDeleteMessage() {
-    throw "not implemented";
+  handleBulkDeleteMessage(data) {
+    data.deleted_ids.forEach((deletedId) => {
+      this.handleDeleteMessage({
+        deleted_id: deletedId,
+        deleted_at: data.deleted_at,
+      });
+    });
   }
 
   handleDeleteMessage(data) {
diff --git a/plugins/chat/spec/lib/chat/message_mover_spec.rb b/plugins/chat/spec/lib/chat/message_mover_spec.rb
index 3c3781be65e..c694b246d9d 100644
--- a/plugins/chat/spec/lib/chat/message_mover_spec.rb
+++ b/plugins/chat/spec/lib/chat/message_mover_spec.rb
@@ -76,7 +76,7 @@ describe Chat::MessageMover do
       deleted_messages = Chat::Message.with_deleted.where(id: move_message_ids).order(:id)
       expect(deleted_messages.count).to eq(3)
       expect(messages.first.channel).to eq("/chat/#{source_channel.id}")
-      expect(messages.first.data[:typ]).to eq("bulk_delete")
+      expect(messages.first.data[:type]).to eq("bulk_delete")
       expect(messages.first.data[:deleted_ids]).to eq(deleted_messages.map(&:id))
       expect(messages.first.data[:deleted_at]).not_to eq(nil)
     end
diff --git a/plugins/chat/spec/models/chat/thread_spec.rb b/plugins/chat/spec/models/chat/thread_spec.rb
index dbed433a1c3..f48a4f04f94 100644
--- a/plugins/chat/spec/models/chat/thread_spec.rb
+++ b/plugins/chat/spec/models/chat/thread_spec.rb
@@ -42,4 +42,107 @@ RSpec.describe Chat::Thread do
       end
     end
   end
+
+  describe ".grouped_messages" do
+    fab!(:channel) { Fabricate(:category_channel) }
+    fab!(:thread_1) { Fabricate(:chat_thread, channel: channel) }
+    fab!(:thread_2) { Fabricate(:chat_thread, channel: channel) }
+
+    fab!(:message_1) { Fabricate(:chat_message, chat_channel: channel, thread: thread_1) }
+    fab!(:message_2) { Fabricate(:chat_message, chat_channel: channel, thread: thread_1) }
+    fab!(:message_3) { Fabricate(:chat_message, chat_channel: channel, thread: thread_2) }
+
+    let(:result) { Chat::Thread.grouped_messages(**params) }
+
+    context "when thread_ids provided" do
+      let(:params) { { thread_ids: [thread_1.id, thread_2.id] } }
+
+      it "groups all the message ids in each thread by thread ID" do
+        expect(result.find { |res| res.thread_id == thread_1.id }.to_h).to eq(
+          {
+            thread_message_ids: [thread_1.original_message_id, message_1.id, message_2.id],
+            thread_id: thread_1.id,
+            original_message_id: thread_1.original_message_id,
+          },
+        )
+        expect(result.find { |res| res.thread_id == thread_2.id }.to_h).to eq(
+          {
+            thread_message_ids: [thread_2.original_message_id, message_3.id],
+            thread_id: thread_2.id,
+            original_message_id: thread_2.original_message_id,
+          },
+        )
+      end
+
+      context "when include_original_message is false" do
+        let(:params) { { thread_ids: [thread_1.id, thread_2.id], include_original_message: false } }
+
+        it "does not include the original message in the thread_message_ids" do
+          expect(result.find { |res| res.thread_id == thread_1.id }.to_h).to eq(
+            {
+              thread_message_ids: [message_1.id, message_2.id],
+              thread_id: thread_1.id,
+              original_message_id: thread_1.original_message_id,
+            },
+          )
+        end
+      end
+    end
+
+    context "when message_ids provided" do
+      let(:params) do
+        {
+          message_ids: [
+            thread_1.original_message_id,
+            thread_2.original_message_id,
+            message_1.id,
+            message_2.id,
+            message_3.id,
+          ],
+        }
+      end
+
+      it "groups all the message ids in each thread by thread ID" do
+        expect(result.find { |res| res.thread_id == thread_1.id }.to_h).to eq(
+          {
+            thread_message_ids: [thread_1.original_message_id, message_1.id, message_2.id],
+            thread_id: thread_1.id,
+            original_message_id: thread_1.original_message_id,
+          },
+        )
+        expect(result.find { |res| res.thread_id == thread_2.id }.to_h).to eq(
+          {
+            thread_message_ids: [thread_2.original_message_id, message_3.id],
+            thread_id: thread_2.id,
+            original_message_id: thread_2.original_message_id,
+          },
+        )
+      end
+
+      context "when include_original_message is false" do
+        let(:params) do
+          {
+            message_ids: [
+              thread_1.original_message_id,
+              thread_2.original_message_id,
+              message_1.id,
+              message_2.id,
+              message_3.id,
+            ],
+            include_original_message: false,
+          }
+        end
+
+        it "does not include the original message in the thread_message_ids" do
+          expect(result.find { |res| res.thread_id == thread_1.id }.to_h).to eq(
+            {
+              thread_message_ids: [message_1.id, message_2.id],
+              thread_id: thread_1.id,
+              original_message_id: thread_1.original_message_id,
+            },
+          )
+        end
+      end
+    end
+  end
 end
diff --git a/plugins/chat/spec/system/deleted_message_spec.rb b/plugins/chat/spec/system/deleted_message_spec.rb
index aa6d4f9237c..384c64d2c1a 100644
--- a/plugins/chat/spec/system/deleted_message_spec.rb
+++ b/plugins/chat/spec/system/deleted_message_spec.rb
@@ -24,4 +24,49 @@ RSpec.describe "Deleted message", type: :system, js: true do
       expect(page).to have_content(I18n.t("js.chat.deleted"))
     end
   end
+
+  context "when bulk deleting messages across the channel and a thread" do
+    let(:side_panel) { PageObjects::Pages::ChatSidePanel.new }
+    let(:open_thread) { PageObjects::Pages::ChatThread.new }
+
+    fab!(:other_user) { Fabricate(:user) }
+    fab!(:message_1) { Fabricate(:chat_message, chat_channel: channel_1, user: other_user) }
+    fab!(:message_2) { Fabricate(:chat_message, chat_channel: channel_1, user: other_user) }
+    fab!(:message_3) { Fabricate(:chat_message, chat_channel: channel_1, user: other_user) }
+
+    fab!(:thread) { Fabricate(:chat_thread, channel: channel_1) }
+    fab!(:message_4) do
+      Fabricate(:chat_message, chat_channel: channel_1, user: other_user, thread: thread)
+    end
+    fab!(:message_5) do
+      Fabricate(:chat_message, chat_channel: channel_1, user: other_user, thread: thread)
+    end
+
+    before do
+      channel_1.update!(threading_enabled: true)
+      SiteSetting.enable_experimental_chat_threaded_discussions = true
+      chat_system_user_bootstrap(user: other_user, channel: channel_1)
+    end
+
+    it "hides the deleted messages" do
+      chat_page.visit_channel(channel_1)
+      channel_page.message_thread_indicator(thread.original_message).click
+      expect(side_panel).to have_open_thread(thread)
+
+      expect(channel_page).to have_message(id: message_1.id)
+      expect(channel_page).to have_message(id: message_2.id)
+      expect(open_thread).to have_message(thread.id, id: message_4.id)
+      expect(open_thread).to have_message(thread.id, id: message_5.id)
+
+      Chat::Publisher.publish_bulk_delete!(
+        channel_1,
+        [message_1.id, message_2.id, message_4.id, message_5.id].flatten,
+      )
+
+      expect(channel_page).to have_no_message(id: message_1.id)
+      expect(channel_page).to have_no_message(id: message_2.id)
+      expect(open_thread).to have_no_message(thread.id, id: message_4.id)
+      expect(open_thread).to have_no_message(thread.id, id: message_5.id)
+    end
+  end
 end
diff --git a/plugins/chat/spec/system/page_objects/chat/chat_channel.rb b/plugins/chat/spec/system/page_objects/chat/chat_channel.rb
index 8d0c8db253b..f2e193ade82 100644
--- a/plugins/chat/spec/system/page_objects/chat/chat_channel.rb
+++ b/plugins/chat/spec/system/page_objects/chat/chat_channel.rb
@@ -157,10 +157,19 @@ module PageObjects
       end
 
       def has_message?(text: nil, id: nil)
+        check_message_presence(exists: true, text: text, id: id)
+      end
+
+      def has_no_message?(text: nil, id: nil)
+        check_message_presence(exists: false, text: text, id: id)
+      end
+
+      def check_message_presence(exists: true, text: nil, id: nil)
+        css_method = exists ? :has_css? : :has_no_css?
         if text
-          has_css?(".chat-message-text", text: text)
+          send(css_method, ".chat-message-text", text: text, wait: 5)
         elsif id
-          has_css?(".chat-message-container[data-id=\"#{id}\"]", wait: 10)
+          send(css_method, ".chat-message-container[data-id=\"#{id}\"]", wait: 10)
         end
       end
 
diff --git a/plugins/chat/spec/system/page_objects/chat/chat_thread.rb b/plugins/chat/spec/system/page_objects/chat/chat_thread.rb
index e9ac6dd96b9..cf857d805fb 100644
--- a/plugins/chat/spec/system/page_objects/chat/chat_thread.rb
+++ b/plugins/chat/spec/system/page_objects/chat/chat_thread.rb
@@ -49,10 +49,25 @@ module PageObjects
       end
 
       def has_message?(thread_id, text: nil, id: nil)
+        check_message_presence(thread_id, exists: true, text: text, id: id)
+      end
+
+      def has_no_message?(thread_id, text: nil, id: nil)
+        check_message_presence(thread_id, exists: false, text: text, id: id)
+      end
+
+      def check_message_presence(thread_id, exists: true, text: nil, id: nil)
+        css_method = exists ? :has_css? : :has_no_css?
         if text
-          find(thread_selector_by_id(thread_id)).has_css?(".chat-message-text", text: text, wait: 5)
+          find(thread_selector_by_id(thread_id)).send(
+            css_method,
+            ".chat-message-text",
+            text: text,
+            wait: 5,
+          )
         elsif id
-          find(thread_selector_by_id(thread_id)).has_css?(
+          find(thread_selector_by_id(thread_id)).send(
+            css_method,
             ".chat-message-container[data-id=\"#{id}\"]",
             wait: 10,
           )