diff --git a/Userland/Libraries/LibWeb/DOM/Attr.cpp b/Userland/Libraries/LibWeb/DOM/Attr.cpp
index fc5ce191f6..527a07d7cd 100644
--- a/Userland/Libraries/LibWeb/DOM/Attr.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Attr.cpp
@@ -18,6 +18,11 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Attr>> Attr::create(Document& document, Dep
     return MUST_OR_THROW_OOM(document.heap().allocate<Attr>(document.realm(), document, QualifiedName(move(local_name), {}, {}), move(value), owner_element));
 }
 
+WebIDL::ExceptionOr<JS::NonnullGCPtr<Attr>> Attr::create(Document& document, QualifiedName qualified_name, DeprecatedString value, Element const* owner_element)
+{
+    return MUST_OR_THROW_OOM(document.heap().allocate<Attr>(document.realm(), document, move(qualified_name), move(value), owner_element));
+}
+
 JS::NonnullGCPtr<Attr> Attr::clone(Document& document)
 {
     return *heap().allocate<Attr>(realm(), document, m_qualified_name, m_value, nullptr).release_allocated_value_but_fixme_should_propagate_errors();
diff --git a/Userland/Libraries/LibWeb/DOM/Attr.h b/Userland/Libraries/LibWeb/DOM/Attr.h
index d3d88bb69d..ee94fd802c 100644
--- a/Userland/Libraries/LibWeb/DOM/Attr.h
+++ b/Userland/Libraries/LibWeb/DOM/Attr.h
@@ -18,7 +18,8 @@ class Attr final : public Node {
     WEB_PLATFORM_OBJECT(Attr, Node);
 
 public:
-    static WebIDL::ExceptionOr<JS::NonnullGCPtr<Attr>> create(Document&, DeprecatedFlyString local_name, DeprecatedString value, Element const* = nullptr);
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<Attr>> create(Document&, QualifiedName, DeprecatedString value = "", Element const* = nullptr);
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<Attr>> create(Document&, DeprecatedFlyString local_name, DeprecatedString value = "", Element const* = nullptr);
     JS::NonnullGCPtr<Attr> clone(Document&);
 
     virtual ~Attr() override = default;
diff --git a/Userland/Libraries/LibWeb/DOM/Element.cpp b/Userland/Libraries/LibWeb/DOM/Element.cpp
index 9bb5861080..7b947883b5 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Element.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2018-2023, Andreas Kling <kling@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -197,6 +197,20 @@ WebIDL::ExceptionOr<void> Element::set_attribute_ns(DeprecatedFlyString const& n
     return set_attribute(extracted_qualified_name.local_name(), value);
 }
 
+// https://dom.spec.whatwg.org/#dom-element-setattributenode
+WebIDL::ExceptionOr<JS::GCPtr<Attr>> Element::set_attribute_node(Attr& attr)
+{
+    // The setAttributeNode(attr) and setAttributeNodeNS(attr) methods steps are to return the result of setting an attribute given attr and this.
+    return m_attributes->set_attribute(attr);
+}
+
+// https://dom.spec.whatwg.org/#dom-element-setattributenodens
+WebIDL::ExceptionOr<JS::GCPtr<Attr>> Element::set_attribute_node_ns(Attr& attr)
+{
+    // The setAttributeNode(attr) and setAttributeNodeNS(attr) methods steps are to return the result of setting an attribute given attr and this.
+    return m_attributes->set_attribute(attr);
+}
+
 // https://dom.spec.whatwg.org/#dom-element-removeattribute
 void Element::remove_attribute(DeprecatedFlyString const& name)
 {
diff --git a/Userland/Libraries/LibWeb/DOM/Element.h b/Userland/Libraries/LibWeb/DOM/Element.h
index e64d1de6dc..db40cf0c21 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.h
+++ b/Userland/Libraries/LibWeb/DOM/Element.h
@@ -71,6 +71,8 @@ public:
     DeprecatedString get_attribute(DeprecatedFlyString const& name) const;
     WebIDL::ExceptionOr<void> set_attribute(DeprecatedFlyString const& name, DeprecatedString const& value);
     WebIDL::ExceptionOr<void> set_attribute_ns(DeprecatedFlyString const& namespace_, DeprecatedFlyString const& qualified_name, DeprecatedString const& value);
+    WebIDL::ExceptionOr<JS::GCPtr<Attr>> set_attribute_node(Attr&);
+    WebIDL::ExceptionOr<JS::GCPtr<Attr>> set_attribute_node_ns(Attr&);
     void remove_attribute(DeprecatedFlyString const& name);
     WebIDL::ExceptionOr<bool> toggle_attribute(DeprecatedFlyString const& name, Optional<bool> force);
     size_t attribute_list_size() const { return m_attributes->length(); }
diff --git a/Userland/Libraries/LibWeb/DOM/Element.idl b/Userland/Libraries/LibWeb/DOM/Element.idl
index 6614c8c841..c933976cf1 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.idl
+++ b/Userland/Libraries/LibWeb/DOM/Element.idl
@@ -30,6 +30,9 @@ interface Element : Node {
     DOMString? getAttribute(DOMString qualifiedName);
     undefined setAttribute(DOMString qualifiedName, DOMString value);
     [CEReactions] undefined setAttributeNS(DOMString? namespace , DOMString qualifiedName , DOMString value);
+    [CEReactions] Attr? setAttributeNode(Attr attr);
+    [CEReactions] Attr? setAttributeNodeNS(Attr attr);
+
     undefined removeAttribute(DOMString qualifiedName);
     [CEReactions] boolean toggleAttribute(DOMString qualifiedName, optional boolean force);
     boolean hasAttribute(DOMString qualifiedName);
diff --git a/Userland/Libraries/LibWeb/DOM/NamedNodeMap.cpp b/Userland/Libraries/LibWeb/DOM/NamedNodeMap.cpp
index 04b9c62d1f..9219add054 100644
--- a/Userland/Libraries/LibWeb/DOM/NamedNodeMap.cpp
+++ b/Userland/Libraries/LibWeb/DOM/NamedNodeMap.cpp
@@ -95,13 +95,13 @@ Attr const* NamedNodeMap::get_named_item_ns(StringView namespace_, StringView lo
 }
 
 // https://dom.spec.whatwg.org/#dom-namednodemap-setnameditem
-WebIDL::ExceptionOr<Attr const*> NamedNodeMap::set_named_item(Attr& attribute)
+WebIDL::ExceptionOr<JS::GCPtr<Attr>> NamedNodeMap::set_named_item(Attr& attribute)
 {
     return set_attribute(attribute);
 }
 
 // https://dom.spec.whatwg.org/#dom-namednodemap-setnameditemns
-WebIDL::ExceptionOr<Attr const*> NamedNodeMap::set_named_item_ns(Attr& attribute)
+WebIDL::ExceptionOr<JS::GCPtr<Attr>> NamedNodeMap::set_named_item_ns(Attr& attribute)
 {
     return set_attribute(attribute);
 }
@@ -195,7 +195,7 @@ Attr const* NamedNodeMap::get_attribute_ns(StringView namespace_, StringView loc
 }
 
 // https://dom.spec.whatwg.org/#concept-element-attributes-set
-WebIDL::ExceptionOr<Attr const*> NamedNodeMap::set_attribute(Attr& attribute)
+WebIDL::ExceptionOr<JS::GCPtr<Attr>> NamedNodeMap::set_attribute(Attr& attribute)
 {
     // 1. If attr’s element is neither null nor element, throw an "InUseAttributeError" DOMException.
     if ((attribute.owner_element() != nullptr) && (attribute.owner_element() != &associated_element()))
diff --git a/Userland/Libraries/LibWeb/DOM/NamedNodeMap.h b/Userland/Libraries/LibWeb/DOM/NamedNodeMap.h
index af46bd3475..9c6cbe7356 100644
--- a/Userland/Libraries/LibWeb/DOM/NamedNodeMap.h
+++ b/Userland/Libraries/LibWeb/DOM/NamedNodeMap.h
@@ -37,8 +37,8 @@ public:
     Attr const* item(u32 index) const;
     Attr const* get_named_item(StringView qualified_name) const;
     Attr const* get_named_item_ns(StringView namespace_, StringView local_name) const;
-    WebIDL::ExceptionOr<Attr const*> set_named_item(Attr& attribute);
-    WebIDL::ExceptionOr<Attr const*> set_named_item_ns(Attr& attribute);
+    WebIDL::ExceptionOr<JS::GCPtr<Attr>> set_named_item(Attr& attribute);
+    WebIDL::ExceptionOr<JS::GCPtr<Attr>> set_named_item_ns(Attr& attribute);
     WebIDL::ExceptionOr<Attr const*> remove_named_item(StringView qualified_name);
     WebIDL::ExceptionOr<Attr const*> remove_named_item_ns(StringView namespace_, StringView local_name);
 
@@ -47,7 +47,7 @@ public:
     Attr* get_attribute_ns(StringView namespace_, StringView local_name, size_t* item_index = nullptr);
     Attr const* get_attribute(StringView qualified_name, size_t* item_index = nullptr) const;
     Attr const* get_attribute_ns(StringView namespace_, StringView local_name, size_t* item_index = nullptr) const;
-    WebIDL::ExceptionOr<Attr const*> set_attribute(Attr& attribute);
+    WebIDL::ExceptionOr<JS::GCPtr<Attr>> set_attribute(Attr& attribute);
     void replace_attribute(Attr& old_attribute, Attr& new_attribute, size_t old_attribute_index);
     void append_attribute(Attr& attribute);
     Attr const* remove_attribute(StringView qualified_name);