diff --git a/actiontext/lib/action_text/engine.rb b/actiontext/lib/action_text/engine.rb
index 9d5fd1dd25..e78c95b69b 100644
--- a/actiontext/lib/action_text/engine.rb
+++ b/actiontext/lib/action_text/engine.rb
@@ -46,7 +46,7 @@ module ActionText
 
     initializer "action_text.renderer" do
       ActiveSupport.on_load(:action_text_content) do
-        self.renderer = Class.new(ActionController::Base).renderer
+        self.default_renderer = Class.new(ActionController::Base).renderer
       end
 
       %i[action_controller_base action_mailer].each do |abstract_controller|
diff --git a/actiontext/lib/action_text/rendering.rb b/actiontext/lib/action_text/rendering.rb
index caef71c6b4..47cced4ce5 100644
--- a/actiontext/lib/action_text/rendering.rb
+++ b/actiontext/lib/action_text/rendering.rb
@@ -8,6 +8,7 @@ module ActionText
     extend ActiveSupport::Concern
 
     included do
+      cattr_accessor :default_renderer, instance_accessor: false
       thread_cattr_accessor :renderer, instance_accessor: false
       delegate :render, to: :class
     end
@@ -22,7 +23,7 @@ module ActionText
       end
 
       def render(*args, &block)
-        renderer.render_to_string(*args, &block)
+        (renderer || default_renderer).render_to_string(*args, &block)
       end
     end
   end
diff --git a/actiontext/test/unit/content_test.rb b/actiontext/test/unit/content_test.rb
index c00ad181a5..dcedb8b1d4 100644
--- a/actiontext/test/unit/content_test.rb
+++ b/actiontext/test/unit/content_test.rb
@@ -116,6 +116,15 @@ class ActionText::ContentTest < ActiveSupport::TestCase
     assert_not defined?(::ApplicationController)
   end
 
+  test "renders with layout when in a new thread" do
+    html = "<h1>Hello world</h1>"
+    rendered = nil
+    Thread.new { rendered = content_from_html(html).to_rendered_html_with_layout }.join
+
+    assert_includes rendered, html
+    assert_match %r/\A#{Regexp.escape '<div class="trix-content">'}/, rendered
+  end
+
   private
     def content_from_html(html)
       ActionText::Content.new(html).tap do |content|