diff --git a/LayoutTests/platform/gtk/TestExpectations b/LayoutTests/platform/gtk/TestExpectations
index ca33eced4a57e..94675bc73b756 100644
--- a/LayoutTests/platform/gtk/TestExpectations
+++ b/LayoutTests/platform/gtk/TestExpectations
@@ -2337,14 +2337,6 @@ fast/mediastream/mediastreamtrack-video-frameRate-clone-decreasing.html [ Crash
 # Trusted Types aren't implemented yet
 webkit.org/b/266630 imported/w3c/web-platform-tests/trusted-types/trusted-types-reporting-check-report.html [ Failure Pass ]
 webkit.org/b/266630 imported/w3c/web-platform-tests/trusted-types/block-string-assignment-to-attribute-via-attribute-node.html [ Failure Pass ]
-webkit.org/b/266630 imported/w3c/web-platform-tests/trusted-types/Element-setAttribute.html [ Failure ]
-webkit.org/b/266630 imported/w3c/web-platform-tests/trusted-types/WorkerGlobalScope-eval.html [ Failure ]
-webkit.org/b/266630 imported/w3c/web-platform-tests/trusted-types/WorkerGlobalScope-importScripts.html [ Failure ]
-webkit.org/b/266630 imported/w3c/web-platform-tests/trusted-types/block-string-assignment-to-Element-setAttribute.html [ Failure ]
-webkit.org/b/266630 imported/w3c/web-platform-tests/trusted-types/block-string-assignment-to-HTMLElement-generic.html [ Failure ]
-webkit.org/b/266630 imported/w3c/web-platform-tests/trusted-types/default-policy-report-only.html [ Failure ]
-webkit.org/b/266630 imported/w3c/web-platform-tests/trusted-types/default-policy.html [ Failure ]
-webkit.org/b/266630 imported/w3c/web-platform-tests/trusted-types/worker-constructor.https.html [ Failure ]
 
 # Flaky tests on Aug-2023
 webkit.org/b/261024 animations/change-completed-animation-transform.html [ ImageOnlyFailure Pass ]
diff --git a/Source/WebCore/dom/Element.cpp b/Source/WebCore/dom/Element.cpp
index 6d66bb6b5288b..be6e98c96d46e 100644
--- a/Source/WebCore/dom/Element.cpp
+++ b/Source/WebCore/dom/Element.cpp
@@ -145,6 +145,7 @@
 #include "StyleTreeResolver.h"
 #include "TextIterator.h"
 #include "TouchAction.h"
+#include "TrustedType.h"
 #include "TypedElementDescendantIteratorInlines.h"
 #include "VisibilityAdjustment.h"
 #include "VoidCallback.h"
@@ -2000,7 +2001,31 @@ ExceptionOr<bool> Element::toggleAttribute(const AtomString& qualifiedName, std:
     return true;
 }
 
-ExceptionOr<void> Element::setAttribute(const AtomString& qualifiedName, const AtomString& value)
+static ExceptionOr<String> getTrustedTypesCompliantAttributeValue(const String& attributeType, const TrustedTypeOrString& value, Element* element, String sink)
+{
+    auto stringValueHolder = WTF::switchOn(value,
+        [&](const String& str) -> ExceptionOr<String> {
+            if (attributeType.isNull())
+                return String(str);
+            return trustedTypeCompliantString(stringToTrustedType(attributeType), *(element->document().scriptExecutionContext()), str, sink);
+        },
+        [](const RefPtr<TrustedHTML>& trustedHTML) -> ExceptionOr<String> {
+            return trustedHTML->toString();
+        },
+        [](const RefPtr<TrustedScript>& trustedScript) -> ExceptionOr<String> {
+            return trustedScript->toString();
+        },
+        [](const RefPtr<TrustedScriptURL>& trustedScriptURL) -> ExceptionOr<String> {
+            return trustedScriptURL->toString();
+        }
+    );
+    if (stringValueHolder.hasException())
+        return stringValueHolder.releaseException();
+
+    return stringValueHolder.releaseReturnValue();
+}
+
+ExceptionOr<void> Element::setAttribute(const AtomString& qualifiedName, const TrustedTypeOrString& value)
 {
     if (!Document::isValidName(qualifiedName))
         return Exception { ExceptionCode::InvalidCharacterError, makeString("Invalid qualified name: '", qualifiedName, "'") };
@@ -2009,8 +2034,18 @@ ExceptionOr<void> Element::setAttribute(const AtomString& qualifiedName, const A
     auto caseAdjustedQualifiedName = shouldIgnoreAttributeCase(*this) ? qualifiedName.convertToASCIILowercase() : qualifiedName;
     unsigned index = elementData() ? elementData()->findAttributeIndexByName(caseAdjustedQualifiedName, false) : ElementData::attributeNotFound;
     auto name = index != ElementData::attributeNotFound ? attributeAt(index).name() : QualifiedName { nullAtom(), caseAdjustedQualifiedName, nullAtom() };
-    setAttributeInternal(index, name, value, InSynchronizationOfLazyAttribute::No);
+    if (!document().scriptExecutionContext()->settingsValues().trustedTypesEnabled)
+        setAttributeInternal(index, name, std::get<AtomString>(value), InSynchronizationOfLazyAttribute::No);
+    else {
+        auto sink = nullString();
+        String attributeType = getTrustedTypeForAttribute(name.localName(), getAttribute(name), ""_s, ""_s);
+        auto attributeValue = getTrustedTypesCompliantAttributeValue(attributeType, value, this, "Element setAttribute"_s);
 
+        if (attributeValue.hasException())
+            return attributeValue.releaseException();
+
+        setAttributeInternal(index, name,  AtomString(attributeValue.releaseReturnValue()), InSynchronizationOfLazyAttribute::No);
+    }
     return { };
 }
 
@@ -2314,7 +2349,7 @@ void Element::setElementsArrayAttribute(const QualifiedName& attributeName, std:
 
     auto newElements = copyToVectorOf<WeakPtr<Element, WeakPtrImplWithEventTargetData>>(*elements);
     explicitlySetAttrElementsMap().set(attributeName, WTFMove(newElements));
-    
+
     if (CheckedPtr cache = document().existingAXObjectCache()) {
         for (auto element : elements.value()) {
             // FIXME: Should this pass `element` instead of `*this`?
@@ -3227,7 +3262,7 @@ static void appendAttributes(StringBuilder& builder, const Element& element)
             classNamesToDump = maxNumClassNames;
             addEllipsis = true;
         }
-        
+
         for (size_t i = 0; i < classNamesToDump; ++i) {
             if (i > 0)
                 builder.append(' ');
@@ -3395,12 +3430,23 @@ ExceptionOr<QualifiedName> Element::parseAttributeName(const AtomString& namespa
     return parsedAttributeName;
 }
 
-ExceptionOr<void> Element::setAttributeNS(const AtomString& namespaceURI, const AtomString& qualifiedName, const AtomString& value)
+ExceptionOr<void> Element::setAttributeNS(const AtomString& namespaceURI, const AtomString& qualifiedName, const TrustedTypeOrString& value)
 {
     auto result = parseAttributeName(namespaceURI, qualifiedName);
     if (result.hasException())
         return result.releaseException();
-    setAttribute(result.releaseReturnValue(), value);
+    if (!document().scriptExecutionContext()->settingsValues().trustedTypesEnabled)
+        setAttribute(result.releaseReturnValue(), std::get<AtomString>(value));
+    else {
+        String attributeType = getTrustedTypeForAttribute(qualifiedName, getAttribute(qualifiedName), ""_s, namespaceURI);
+        auto attributeValue = getTrustedTypesCompliantAttributeValue(attributeType, value, this, "Element setAttributeNS"_s);
+
+        if (attributeValue.hasException())
+            return attributeValue.releaseException();
+
+        setAttribute(result.releaseReturnValue(), AtomString(attributeValue.releaseReturnValue()));
+    }
+
     return { };
 }
 
diff --git a/Source/WebCore/dom/Element.h b/Source/WebCore/dom/Element.h
index cca88e29c4b48..ac44569f80c4e 100644
--- a/Source/WebCore/dom/Element.h
+++ b/Source/WebCore/dom/Element.h
@@ -35,6 +35,9 @@
 #include "ScrollTypes.h"
 #include "ShadowRootMode.h"
 #include "SimulatedClickOptions.h"
+#include "TrustedHTML.h"
+#include "TrustedScript.h"
+#include "TrustedScriptURL.h"
 #include "WebAnimationTypes.h"
 #include <JavaScriptCore/Forward.h>
 
@@ -119,6 +122,7 @@ struct ShadowRootInit;
 
 using ElementName = NodeName;
 using ExplicitlySetAttrElementsMap = HashMap<QualifiedName, Vector<WeakPtr<Element, WeakPtrImplWithEventTargetData>>>;
+using TrustedTypeOrString = std::variant<RefPtr<TrustedHTML>, RefPtr<TrustedScript>, RefPtr<TrustedScriptURL>, AtomString>;
 
 // https://drafts.csswg.org/css-contain/#relevant-to-the-user
 enum class ContentRelevancy : uint8_t {
@@ -190,9 +194,9 @@ class Element : public ContainerNode {
     AtomString getAttributeForBindings(const AtomString& qualifiedName, ResolveURLs = ResolveURLs::NoExcludingURLsForPrivacy) const;
     inline AtomString getAttributeNSForBindings(const AtomString& namespaceURI, const AtomString& localName, ResolveURLs = ResolveURLs::NoExcludingURLsForPrivacy) const;
 
-    WEBCORE_EXPORT ExceptionOr<void> setAttribute(const AtomString& qualifiedName, const AtomString& value);
+    WEBCORE_EXPORT ExceptionOr<void> setAttribute(const AtomString& qualifiedName, const TrustedTypeOrString& value);
     static ExceptionOr<QualifiedName> parseAttributeName(const AtomString& namespaceURI, const AtomString& qualifiedName);
-    WEBCORE_EXPORT ExceptionOr<void> setAttributeNS(const AtomString& namespaceURI, const AtomString& qualifiedName, const AtomString& value);
+    WEBCORE_EXPORT ExceptionOr<void> setAttributeNS(const AtomString& namespaceURI, const AtomString& qualifiedName, const TrustedTypeOrString& value);
 
     ExceptionOr<bool> toggleAttribute(const AtomString& qualifiedName, std::optional<bool> force);
 
diff --git a/Source/WebCore/dom/Element.idl b/Source/WebCore/dom/Element.idl
index d0220b77a96d7..40cc8fb070fc2 100644
--- a/Source/WebCore/dom/Element.idl
+++ b/Source/WebCore/dom/Element.idl
@@ -42,8 +42,8 @@
     sequence<DOMString> getAttributeNames();
     [DOMJIT=ReadDOM, ImplementedAs=getAttributeForBindings] DOMString? getAttribute([AtomString] DOMString qualifiedName);
     [ImplementedAs=getAttributeNSForBindings] DOMString? getAttributeNS([AtomString] DOMString? namespaceURI, [AtomString] DOMString localName);
-    [CEReactions=Needed] undefined setAttribute([AtomString] DOMString qualifiedName, [AtomString] DOMString value);
-    [CEReactions=Needed] undefined setAttributeNS([AtomString] DOMString? namespaceURI, [AtomString] DOMString qualifiedName, [AtomString] DOMString value);
+    [CEReactions=Needed] undefined setAttribute([AtomString] DOMString qualifiedName, (TrustedType or [AtomString] DOMString) value);
+    [CEReactions=Needed] undefined setAttributeNS([AtomString] DOMString? namespaceURI, [AtomString] DOMString qualifiedName, (TrustedType or [AtomString] DOMString) value);
     [CEReactions=Needed, ImplementedAs=removeAttributeForBindings] undefined removeAttribute([AtomString] DOMString qualifiedName);
     [CEReactions=Needed, ImplementedAs=removeAttributeNSForBindings] undefined removeAttributeNS([AtomString] DOMString? namespaceURI, [AtomString] DOMString localName);
     [CEReactions=Needed] boolean toggleAttribute([AtomString] DOMString qualifiedName, optional boolean force);
@@ -106,3 +106,5 @@ Element includes NonDocumentTypeChildNode;
 Element includes ParentNode;
 Element includes Slotable;
 Element includes InnerHTML;
+
+typedef (TrustedHTML or TrustedScript or TrustedScriptURL) TrustedType;
diff --git a/Source/WebCore/dom/TrustedScript.h b/Source/WebCore/dom/TrustedScript.h
index ba1c1d06e2a7c..7c1c7cd784568 100644
--- a/Source/WebCore/dom/TrustedScript.h
+++ b/Source/WebCore/dom/TrustedScript.h
@@ -29,7 +29,7 @@
 
 namespace WebCore {
 
-class TrustedScript final : public ScriptWrappable, public RefCounted<TrustedScript> {
+class WEBCORE_EXPORT TrustedScript final : public ScriptWrappable, public RefCounted<TrustedScript> {
     WTF_MAKE_ISO_ALLOCATED(TrustedScript);
 public:
     static Ref<TrustedScript> create(const String& data);
diff --git a/Source/WebCore/dom/TrustedScriptURL.h b/Source/WebCore/dom/TrustedScriptURL.h
index fb2cbf4eadaf7..a0deb79cf2202 100644
--- a/Source/WebCore/dom/TrustedScriptURL.h
+++ b/Source/WebCore/dom/TrustedScriptURL.h
@@ -31,7 +31,7 @@
 
 namespace WebCore {
 
-class TrustedScriptURL : public ScriptWrappable, public RefCounted<TrustedScriptURL> {
+class WEBCORE_EXPORT TrustedScriptURL : public ScriptWrappable, public RefCounted<TrustedScriptURL> {
     WTF_MAKE_ISO_ALLOCATED(TrustedScriptURL);
 public:
     static Ref<TrustedScriptURL> create(const String& data);
diff --git a/Source/WebCore/dom/TrustedType.cpp b/Source/WebCore/dom/TrustedType.cpp
index 6578c0cbcf344..24456ee332675 100644
--- a/Source/WebCore/dom/TrustedType.cpp
+++ b/Source/WebCore/dom/TrustedType.cpp
@@ -37,6 +37,7 @@
 #include "TrustedTypePolicyFactory.h"
 #include "WindowOrWorkerGlobalScopeTrustedTypes.h"
 #include "WorkerGlobalScope.h"
+#include "XLinkNames.h"
 #include <JavaScriptCore/HeapInlines.h>
 #include <JavaScriptCore/JSCInlines.h>
 #include <JavaScriptCore/JSCJSValueInlines.h>
@@ -84,6 +85,19 @@ ASCIILiteral trustedTypeToString(TrustedType trustedType)
     return { };
 }
 
+TrustedType stringToTrustedType(String str)
+{
+    if (str == "TrustedHTML"_s)
+        return TrustedType::TrustedHTML;
+    if (str == "TrustedScript"_s)
+        return TrustedType::TrustedScript;
+    if (str == "TrustedScriptURL"_s)
+        return TrustedType::TrustedScriptURL;
+
+    ASSERT_NOT_REACHED();
+    return { };
+}
+
 ASCIILiteral trustedTypeToCallbackName(TrustedType trustedType)
 {
     switch (trustedType) {
@@ -173,6 +187,30 @@ ExceptionOr<String> trustedTypeCompliantString(TrustedType expectedType, ScriptE
     return stringValue;
 }
 
+String getTrustedTypeForAttribute(const String& tagName, const String& attributeParameter, const String& elementNamespace, const String& attributeNamespace)
+{
+    auto localName = tagName.convertToASCIILowercase();
+    auto attributeName = attributeParameter.convertToASCIILowercase();
+
+    if (attributeName.startsWith("on"_s))
+        return trustedTypeToString(TrustedType::TrustedScript);
+
+    AtomString elementNS = elementNamespace.isEmpty() ? HTMLNames::xhtmlNamespaceURI : AtomString(elementNamespace);
+    AtomString attributeNS = attributeNamespace.isEmpty() ? nullAtom() : AtomString(attributeNamespace);
+
+    QualifiedName element(nullAtom(), AtomString(localName), elementNS);
+    QualifiedName attribute(nullAtom(), AtomString(attributeName), attributeNS);
+
+    if (element.matches(HTMLNames::iframeTag) && attribute.matches(HTMLNames::srcdocAttr))
+        return trustedTypeToString(TrustedType::TrustedHTML);
+    if (element.matches(HTMLNames::scriptTag) && attribute.matches(HTMLNames::srcAttr))
+        return trustedTypeToString(TrustedType::TrustedScriptURL);
+    if (element.matches(SVGNames::scriptTag) && (attribute.matches(SVGNames::hrefAttr) || attribute.matches(XLinkNames::hrefAttr)))
+        return trustedTypeToString(TrustedType::TrustedScriptURL);
+
+    return nullString();
+}
+
 // https://w3c.github.io/trusted-types/dist/spec/#require-trusted-types-for-pre-navigation-check
 ExceptionOr<String> requireTrustedTypesForPreNavigationCheckPasses(ScriptExecutionContext& scriptExecutionContext, const String& urlString)
 {
diff --git a/Source/WebCore/dom/TrustedType.h b/Source/WebCore/dom/TrustedType.h
index 5135d54dae49c..b2e44bc1bd770 100644
--- a/Source/WebCore/dom/TrustedType.h
+++ b/Source/WebCore/dom/TrustedType.h
@@ -45,6 +45,7 @@ enum class TrustedType : int8_t {
 };
 
 ASCIILiteral trustedTypeToString(TrustedType);
+TrustedType stringToTrustedType(String);
 ASCIILiteral trustedTypeToCallbackName(TrustedType);
 
 WEBCORE_EXPORT std::variant<std::monostate, Exception, Ref<TrustedHTML>, Ref<TrustedScript>, Ref<TrustedScriptURL>> processValueWithDefaultPolicy(ScriptExecutionContext&, TrustedType, const String& input, const String& sink);
@@ -55,4 +56,5 @@ WEBCORE_EXPORT ExceptionOr<String> requireTrustedTypesForPreNavigationCheckPasse
 
 ExceptionOr<RefPtr<Text>> processNodeOrStringAsTrustedType(Ref<Document>, RefPtr<Node> parent, std::variant<RefPtr<Node>, String, RefPtr<TrustedScript>>);
 
+WEBCORE_EXPORT String getTrustedTypeForAttribute(const String& tagName, const String& attributeParameter, const String& elementNamespace, const String& attributeNamespace);
 } // namespace WebCore
diff --git a/Source/WebCore/dom/TrustedTypePolicyFactory.cpp b/Source/WebCore/dom/TrustedTypePolicyFactory.cpp
index e475f5a75595e..b0963ef55038f 100644
--- a/Source/WebCore/dom/TrustedTypePolicyFactory.cpp
+++ b/Source/WebCore/dom/TrustedTypePolicyFactory.cpp
@@ -108,26 +108,7 @@ Ref<TrustedScript> TrustedTypePolicyFactory::emptyScript() const
 
 String TrustedTypePolicyFactory::getAttributeType(const String& tagName, const String& attributeParameter, const String& elementNamespace, const String& attributeNamespace) const
 {
-    auto localName = tagName.convertToASCIILowercase();
-    auto attributeName = attributeParameter.convertToASCIILowercase();
-
-    if (attributeName.startsWith("on"_s))
-        return trustedTypeToString(TrustedType::TrustedScript);
-
-    AtomString elementNS = elementNamespace.isEmpty() ? HTMLNames::xhtmlNamespaceURI : AtomString(elementNamespace);
-    AtomString attributeNS = attributeNamespace.isEmpty() ? nullAtom() : AtomString(attributeNamespace);
-
-    QualifiedName element(nullAtom(), AtomString(localName), elementNS);
-    QualifiedName attribute(nullAtom(), AtomString(attributeName), attributeNS);
-
-    if (element.matches(HTMLNames::iframeTag) && attribute.matches(HTMLNames::srcdocAttr))
-        return trustedTypeToString(TrustedType::TrustedHTML);
-    if (element.matches(HTMLNames::scriptTag) && attribute.matches(HTMLNames::srcAttr))
-        return trustedTypeToString(TrustedType::TrustedScriptURL);
-    if (element.matches(SVGNames::scriptTag) && (attribute.matches(SVGNames::hrefAttr) || attribute.matches(XLinkNames::hrefAttr)))
-        return trustedTypeToString(TrustedType::TrustedScriptURL);
-
-    return nullString();
+    return getTrustedTypeForAttribute(tagName, attributeParameter, elementNamespace, attributeNamespace);
 }
 
 String TrustedTypePolicyFactory::getPropertyType(const String& tagName, const String& property, const String& elementNamespace) const