diff --git a/engine/app/controllers/coplan/notifications_controller.rb b/engine/app/controllers/coplan/notifications_controller.rb
index 2c6886e..8efbcbe 100644
--- a/engine/app/controllers/coplan/notifications_controller.rb
+++ b/engine/app/controllers/coplan/notifications_controller.rb
@@ -45,7 +45,20 @@ def mark_all_read
 
       broadcast_badge_update
 
-      redirect_to notifications_path, notice: "All notifications marked as read."
+      respond_to do |format|
+        format.turbo_stream {
+          @notifications = current_user.notifications
+            .includes(:plan, :comment, comment_thread: [:created_by_user])
+            .newest_first
+            .unread
+          @unread_count = 0
+          render turbo_stream: [
+            turbo_stream.update("inbox-badge", "0"),
+            turbo_stream.replace("inbox-panel", partial: "coplan/notifications/panel")
+          ]
+        }
+        format.html { redirect_to notifications_path, notice: "All notifications marked as read." }
+      end
     end
 
     private
diff --git a/engine/app/views/coplan/notifications/_panel.html.erb b/engine/app/views/coplan/notifications/_panel.html.erb
index 6690614..aa97038 100644
--- a/engine/app/views/coplan/notifications/_panel.html.erb
+++ b/engine/app/views/coplan/notifications/_panel.html.erb
@@ -2,7 +2,7 @@
 <div class="inbox-panel__header">
   <span class="inbox-panel__title">Inbox</span>
   <% if @unread_count > 0 %>
-    <%= button_to "Mark all read", mark_all_read_notifications_path, method: :post, class: "btn btn--secondary btn--sm", data: { turbo: false } %>
+    <%= button_to "Mark all read", mark_all_read_notifications_path, method: :post, class: "btn btn--secondary btn--sm", form: { data: { turbo_stream: true } } %>
   <% end %>
 </div>
 
diff --git a/spec/requests/notifications_spec.rb b/spec/requests/notifications_spec.rb
index 0ff432b..dd3497c 100644
--- a/spec/requests/notifications_spec.rb
+++ b/spec/requests/notifications_spec.rb
@@ -84,5 +84,19 @@
       post mark_all_read_notifications_path
       expect(other_notification.reload.read_at).to be_nil
     end
+
+    it "responds with a turbo_stream that updates the badge and replaces the inbox panel" do
+      create(:notification, user: user, plan: plan, comment_thread: thread)
+
+      post mark_all_read_notifications_path, headers: { "Accept" => "text/vnd.turbo-stream.html" }
+
+      expect(response).to have_http_status(:ok)
+      expect(response.media_type).to eq(Mime[:turbo_stream])
+      expect(response.body).to include('target="inbox-badge"')
+      expect(response.body).to include('action="update"')
+      expect(response.body).to include('target="inbox-panel"')
+      expect(response.body).to include('action="replace"')
+      expect(user.notifications.unread.count).to eq(0)
+    end
   end
 end