diff --git a/Userland/Libraries/LibWeb/HTML/Navigable.cpp b/Userland/Libraries/LibWeb/HTML/Navigable.cpp
index 9503eb0c3f..705fc9f91f 100644
--- a/Userland/Libraries/LibWeb/HTML/Navigable.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Navigable.cpp
@@ -193,6 +193,19 @@ JS::GCPtr<NavigableContainer> Navigable::container() const
     return NavigableContainer::navigable_container_with_content_navigable(const_cast<Navigable&>(*this));
 }
 
+// https://html.spec.whatwg.org/multipage/document-sequences.html#nav-container-document
+JS::GCPtr<DOM::Document> Navigable::container_document() const
+{
+    auto container = this->container();
+
+    // 1. If navigable's container is null, then return null.
+    if (!container)
+        return nullptr;
+
+    // 2. Return navigable's container's node document.
+    return container->document();
+}
+
 // https://html.spec.whatwg.org/multipage/document-sequences.html#nav-traversable
 JS::GCPtr<TraversableNavigable> Navigable::traversable_navigable() const
 {
diff --git a/Userland/Libraries/LibWeb/HTML/Navigable.h b/Userland/Libraries/LibWeb/HTML/Navigable.h
index 112d70f1cd..e40ff78494 100644
--- a/Userland/Libraries/LibWeb/HTML/Navigable.h
+++ b/Userland/Libraries/LibWeb/HTML/Navigable.h
@@ -60,6 +60,7 @@ public:
     String target_name() const;
 
     JS::GCPtr<NavigableContainer> container() const;
+    JS::GCPtr<DOM::Document> container_document() const;
 
     JS::GCPtr<TraversableNavigable> traversable_navigable() const;
     JS::GCPtr<TraversableNavigable> top_level_traversable();