diff --git a/Tests/LibWeb/Text/expected/HTML/outerHTML.txt b/Tests/LibWeb/Text/expected/HTML/outerHTML.txt
new file mode 100644
index 00000000000..4a0892c782c
--- /dev/null
+++ b/Tests/LibWeb/Text/expected/HTML/outerHTML.txt
@@ -0,0 +1,2 @@
+hello students  outerHTML: <div id="foo"><b>hello students</b></div>
+innerHTML: <b>hello students</b>
diff --git a/Tests/LibWeb/Text/input/HTML/outerHTML.html b/Tests/LibWeb/Text/input/HTML/outerHTML.html
new file mode 100644
index 00000000000..8b56d5aca4b
--- /dev/null
+++ b/Tests/LibWeb/Text/input/HTML/outerHTML.html
@@ -0,0 +1,8 @@
+<script src="../include.js"></script>
+<div id="foo"><b>hello students</b></div>
+<script>
+    test(() => {
+        println("outerHTML: " + foo.outerHTML)
+        println("innerHTML: " + foo.innerHTML)
+    });
+</script>
diff --git a/Userland/Libraries/LibWeb/DOM/Element.cpp b/Userland/Libraries/LibWeb/DOM/Element.cpp
index e65095028f4..e52a980331b 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Element.cpp
@@ -1402,6 +1402,19 @@ bool Element::is_actually_disabled() const
     return false;
 }
 
+// https://w3c.github.io/DOM-Parsing/#dom-element-outerhtml
+WebIDL::ExceptionOr<String> Element::outer_html() const
+{
+    return serialize_fragment(DOMParsing::RequireWellFormed::Yes, FragmentSerializationMode::Outer);
+}
+
+// https://w3c.github.io/DOM-Parsing/#dom-element-outerhtml
+WebIDL::ExceptionOr<void> Element::set_outer_html(String const&)
+{
+    dbgln("FIXME: Implement Element::set_outer_html()");
+    return {};
+}
+
 // https://w3c.github.io/DOM-Parsing/#dom-element-insertadjacenthtml
 WebIDL::ExceptionOr<void> Element::insert_adjacent_html(String const& position, String const& text)
 {
diff --git a/Userland/Libraries/LibWeb/DOM/Element.h b/Userland/Libraries/LibWeb/DOM/Element.h
index 33385221feb..81526c0e957 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.h
+++ b/Userland/Libraries/LibWeb/DOM/Element.h
@@ -175,6 +175,9 @@ public:
 
     WebIDL::ExceptionOr<void> insert_adjacent_html(String const& position, String const& text);
 
+    WebIDL::ExceptionOr<String> outer_html() const;
+    WebIDL::ExceptionOr<void> set_outer_html(String const&);
+
     bool is_focused() const;
     bool is_active() const;
     bool is_target() const;
diff --git a/Userland/Libraries/LibWeb/DOM/Element.idl b/Userland/Libraries/LibWeb/DOM/Element.idl
index 390a04e9770..e13fd33a116 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.idl
+++ b/Userland/Libraries/LibWeb/DOM/Element.idl
@@ -85,6 +85,8 @@ interface Element : Node {
     undefined insertAdjacentText(DOMString where, DOMString data);
     [CEReactions] undefined insertAdjacentHTML(DOMString position, DOMString text);
 
+    [CEReactions, LegacyNullToEmptyString] attribute DOMString outerHTML;
+
     undefined scrollIntoView(optional (boolean or ScrollIntoViewOptions) arg = {});
 
     undefined scroll(optional ScrollToOptions options = {});
diff --git a/Userland/Libraries/LibWeb/DOM/Node.cpp b/Userland/Libraries/LibWeb/DOM/Node.cpp
index 3e9e35d81d3..e0da6612b78 100644
--- a/Userland/Libraries/LibWeb/DOM/Node.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Node.cpp
@@ -1336,14 +1336,14 @@ void Node::string_replace_all(String const& string)
 }
 
 // https://w3c.github.io/DOM-Parsing/#dfn-fragment-serializing-algorithm
-WebIDL::ExceptionOr<String> Node::serialize_fragment(DOMParsing::RequireWellFormed require_well_formed) const
+WebIDL::ExceptionOr<String> Node::serialize_fragment(DOMParsing::RequireWellFormed require_well_formed, FragmentSerializationMode fragment_serialization_mode) const
 {
     // 1. Let context document be the value of node's node document.
     auto const& context_document = document();
 
     // 2. If context document is an HTML document, return an HTML serialization of node.
     if (context_document.is_html_document())
-        return HTML::HTMLParser::serialize_html_fragment(*this);
+        return HTML::HTMLParser::serialize_html_fragment(*this, fragment_serialization_mode);
 
     // 3. Otherwise, context document is an XML document; return an XML serialization of node passing the flag require well-formed.
     return DOMParsing::serialize_node_to_xml_string(*this, require_well_formed);
diff --git a/Userland/Libraries/LibWeb/DOM/Node.h b/Userland/Libraries/LibWeb/DOM/Node.h
index 4dc1d9d07bf..24284249fc2 100644
--- a/Userland/Libraries/LibWeb/DOM/Node.h
+++ b/Userland/Libraries/LibWeb/DOM/Node.h
@@ -45,6 +45,11 @@ struct GetRootNodeOptions {
     bool composed { false };
 };
 
+enum class FragmentSerializationMode {
+    Inner,
+    Outer,
+};
+
 class Node : public EventTarget {
     WEB_PLATFORM_OBJECT(Node, EventTarget);
 
@@ -242,7 +247,7 @@ public:
     i32 unique_id() const { return m_unique_id; }
     static Node* from_unique_id(i32);
 
-    WebIDL::ExceptionOr<String> serialize_fragment(DOMParsing::RequireWellFormed) const;
+    WebIDL::ExceptionOr<String> serialize_fragment(DOMParsing::RequireWellFormed, FragmentSerializationMode = FragmentSerializationMode::Inner) const;
 
     void replace_all(JS::GCPtr<Node>);
     void string_replace_all(String const&);
diff --git a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
index 0aa11a26ff4..af761cdcd92 100644
--- a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
@@ -4275,8 +4275,89 @@ static String escape_string(StringView string, AttributeMode attribute_mode)
 }
 
 // https://html.spec.whatwg.org/multipage/parsing.html#html-fragment-serialisation-algorithm
-String HTMLParser::serialize_html_fragment(DOM::Node const& node)
+String HTMLParser::serialize_html_fragment(DOM::Node const& node, DOM::FragmentSerializationMode fragment_serialization_mode)
 {
+    // NOTE: Steps in this function are jumbled a bit to accommodate the Element.outerHTML API.
+    //       When called with FragmentSerializationMode::Outer, we will serialize the element itself,
+    //       not just its children.
+
+    // 2. Let s be a string, and initialize it to the empty string.
+    StringBuilder builder;
+
+    auto serialize_element = [&](DOM::Element const& element) {
+        // 1. If current node is an element in the HTML namespace, the MathML namespace, or the SVG namespace, then let tagname be current node's local name.
+        //    Otherwise, let tagname be current node's qualified name.
+        FlyString tag_name;
+
+        if (element.namespace_uri().has_value() && element.namespace_uri()->is_one_of(Namespace::HTML, Namespace::MathML, Namespace::SVG))
+            tag_name = element.local_name();
+        else
+            tag_name = element.qualified_name();
+
+        // 2. Append a U+003C LESS-THAN SIGN character (<), followed by tagname.
+        builder.append('<');
+        builder.append(tag_name);
+
+        // 3. If current node's is value is not null, and the element does not have an is attribute in its attribute list,
+        //    then append the string " is="", followed by current node's is value escaped as described below in attribute mode,
+        //    followed by a U+0022 QUOTATION MARK character (").
+        if (element.is_value().has_value() && !element.has_attribute(AttributeNames::is)) {
+            builder.append(" is=\""sv);
+            builder.append(escape_string(element.is_value().value(), AttributeMode::Yes));
+            builder.append('"');
+        }
+
+        // 4. For each attribute that the element has, append a U+0020 SPACE character, the attribute's serialized name as described below, a U+003D EQUALS SIGN character (=),
+        //    a U+0022 QUOTATION MARK character ("), the attribute's value, escaped as described below in attribute mode, and a second U+0022 QUOTATION MARK character (").
+        //    NOTE: The order of attributes is implementation-defined. The only constraint is that the order must be stable.
+        element.for_each_attribute([&](auto const& attribute) {
+            builder.append(' ');
+
+            // An attribute's serialized name for the purposes of the previous paragraph must be determined as follows:
+
+            // NOTE: As far as I can tell, these steps are equivalent to just using the qualified name.
+            //
+            // -> If the attribute has no namespace:
+            //         The attribute's serialized name is the attribute's local name.
+            // -> If the attribute is in the XML namespace:
+            //         The attribute's serialized name is the string "xml:" followed by the attribute's local name.
+            // -> If the attribute is in the XMLNS namespace and the attribute's local name is xmlns:
+            //         The attribute's serialized name is the string "xmlns".
+            // -> If the attribute is in the XMLNS namespace and the attribute's local name is not xmlns:
+            //         The attribute's serialized name is the string "xmlns:" followed by the attribute's local name.
+            // -> If the attribute is in the XLink namespace:
+            //         The attribute's serialized name is the string "xlink:" followed by the attribute's local name.
+            // -> If the attribute is in some other namespace:
+            //         The attribute's serialized name is the attribute's qualified name.
+            builder.append(attribute.name());
+
+            builder.append("=\""sv);
+            builder.append(escape_string(attribute.value(), AttributeMode::Yes));
+            builder.append('"');
+        });
+
+        // 5. Append a U+003E GREATER-THAN SIGN character (>).
+        builder.append('>');
+
+        // 6. If current node serializes as void, then continue on to the next child node at this point.
+        if (element.serializes_as_void())
+            return IterationDecision::Continue;
+
+        // 7. Append the value of running the HTML fragment serialization algorithm on the current node element (thus recursing into this algorithm for that element),
+        //    followed by a U+003C LESS-THAN SIGN character (<), a U+002F SOLIDUS character (/), tagname again, and finally a U+003E GREATER-THAN SIGN character (>).
+        builder.append(serialize_html_fragment(element));
+        builder.append("</"sv);
+        builder.append(tag_name);
+        builder.append('>');
+
+        return IterationDecision::Continue;
+    };
+
+    if (fragment_serialization_mode == DOM::FragmentSerializationMode::Outer) {
+        serialize_element(verify_cast<DOM::Element>(node));
+        return builder.to_string_without_validation();
+    }
+
     // The algorithm takes as input a DOM Element, Document, or DocumentFragment referred to as the node.
     VERIFY(node.is_element() || node.is_document() || node.is_document_fragment());
     JS::NonnullGCPtr<DOM::Node const> actual_node = node;
@@ -4295,9 +4376,6 @@ String HTMLParser::serialize_html_fragment(DOM::Node const& node)
             actual_node = verify_cast<HTML::HTMLTemplateElement>(element).content();
     }
 
-    // 2. Let s be a string, and initialize it to the empty string.
-    StringBuilder builder;
-
     // 4. For each child node of the node, in tree order, run the following steps:
     actual_node->for_each_child([&](DOM::Node& current_node) {
         // 1. Let current node be the child node being processed.
@@ -4307,73 +4385,7 @@ String HTMLParser::serialize_html_fragment(DOM::Node const& node)
         if (is<DOM::Element>(current_node)) {
             // -> If current node is an Element
             auto& element = verify_cast<DOM::Element>(current_node);
-
-            // 1. If current node is an element in the HTML namespace, the MathML namespace, or the SVG namespace, then let tagname be current node's local name.
-            //    Otherwise, let tagname be current node's qualified name.
-            FlyString tag_name;
-
-            if (element.namespace_uri().has_value() && element.namespace_uri()->is_one_of(Namespace::HTML, Namespace::MathML, Namespace::SVG))
-                tag_name = element.local_name();
-            else
-                tag_name = element.qualified_name();
-
-            // 2. Append a U+003C LESS-THAN SIGN character (<), followed by tagname.
-            builder.append('<');
-            builder.append(tag_name);
-
-            // 3. If current node's is value is not null, and the element does not have an is attribute in its attribute list,
-            //    then append the string " is="", followed by current node's is value escaped as described below in attribute mode,
-            //    followed by a U+0022 QUOTATION MARK character (").
-            if (element.is_value().has_value() && !element.has_attribute(AttributeNames::is)) {
-                builder.append(" is=\""sv);
-                builder.append(escape_string(element.is_value().value(), AttributeMode::Yes));
-                builder.append('"');
-            }
-
-            // 4. For each attribute that the element has, append a U+0020 SPACE character, the attribute's serialized name as described below, a U+003D EQUALS SIGN character (=),
-            //    a U+0022 QUOTATION MARK character ("), the attribute's value, escaped as described below in attribute mode, and a second U+0022 QUOTATION MARK character (").
-            //    NOTE: The order of attributes is implementation-defined. The only constraint is that the order must be stable.
-            element.for_each_attribute([&](auto const& attribute) {
-                builder.append(' ');
-
-                // An attribute's serialized name for the purposes of the previous paragraph must be determined as follows:
-
-                // NOTE: As far as I can tell, these steps are equivalent to just using the qualified name.
-                //
-                // -> If the attribute has no namespace:
-                //         The attribute's serialized name is the attribute's local name.
-                // -> If the attribute is in the XML namespace:
-                //         The attribute's serialized name is the string "xml:" followed by the attribute's local name.
-                // -> If the attribute is in the XMLNS namespace and the attribute's local name is xmlns:
-                //         The attribute's serialized name is the string "xmlns".
-                // -> If the attribute is in the XMLNS namespace and the attribute's local name is not xmlns:
-                //         The attribute's serialized name is the string "xmlns:" followed by the attribute's local name.
-                // -> If the attribute is in the XLink namespace:
-                //         The attribute's serialized name is the string "xlink:" followed by the attribute's local name.
-                // -> If the attribute is in some other namespace:
-                //         The attribute's serialized name is the attribute's qualified name.
-                builder.append(attribute.name());
-
-                builder.append("=\""sv);
-                builder.append(escape_string(attribute.value(), AttributeMode::Yes));
-                builder.append('"');
-            });
-
-            // 5. Append a U+003E GREATER-THAN SIGN character (>).
-            builder.append('>');
-
-            // 6. If current node serializes as void, then continue on to the next child node at this point.
-            if (element.serializes_as_void())
-                return IterationDecision::Continue;
-
-            // 7. Append the value of running the HTML fragment serialization algorithm on the current node element (thus recursing into this algorithm for that element),
-            //    followed by a U+003C LESS-THAN SIGN character (<), a U+002F SOLIDUS character (/), tagname again, and finally a U+003E GREATER-THAN SIGN character (>).
-            builder.append(serialize_html_fragment(element));
-            builder.append("</"sv);
-            builder.append(tag_name);
-            builder.append('>');
-
-            return IterationDecision::Continue;
+            return serialize_element(element);
         }
 
         if (is<DOM::Text>(current_node)) {
diff --git a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.h b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.h
index c170a6d2442..0fab40d2fdc 100644
--- a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.h
+++ b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.h
@@ -61,7 +61,7 @@ public:
     DOM::Document& document();
 
     static Vector<JS::Handle<DOM::Node>> parse_html_fragment(DOM::Element& context_element, StringView);
-    static String serialize_html_fragment(DOM::Node const& node);
+    static String serialize_html_fragment(DOM::Node const& node, DOM::FragmentSerializationMode = DOM::FragmentSerializationMode::Inner);
 
     enum class InsertionMode {
 #define __ENUMERATE_INSERTION_MODE(mode) mode,