diff --git a/src/browser/BrowserCbor.cpp b/src/browser/BrowserCbor.cpp
index e0f05d34e..7b151c410 100644
--- a/src/browser/BrowserCbor.cpp
+++ b/src/browser/BrowserCbor.cpp
@@ -141,6 +141,8 @@ QByteArray BrowserCbor::cborEncodeExtensionData(const QJsonObject& extensions) c
     QCborStreamWriter writer(&result);
 
     writer.startMap(extensions.keys().count());
+
+    // https://w3c.github.io/webauthn/#sctn-authenticator-credential-properties-extension
     if (extensions["credProps"].toBool()) {
         writer.append("credProps");
         writer.startMap(1);
@@ -149,6 +151,7 @@ QByteArray BrowserCbor::cborEncodeExtensionData(const QJsonObject& extensions) c
         writer.endMap();
     }
 
+    // https://w3c.github.io/webauthn/#sctn-uvm-extension
     if (extensions["uvm"].toBool()) {
         writer.append("uvm");
 
@@ -167,6 +170,7 @@ QByteArray BrowserCbor::cborEncodeExtensionData(const QJsonObject& extensions) c
         writer.endArray();
         writer.endArray();
     }
+
     writer.endMap();
 
     return result;
diff --git a/src/browser/BrowserPasskeys.cpp b/src/browser/BrowserPasskeys.cpp
index b1dfe5120..3e81a25f7 100644
--- a/src/browser/BrowserPasskeys.cpp
+++ b/src/browser/BrowserPasskeys.cpp
@@ -106,6 +106,7 @@ PublicKeyCredential BrowserPasskeys::buildRegisterPublicKeyCredential(const QJso
     QJsonObject responseObject;
     responseObject["attestationObject"] = browserMessageBuilder()->getBase64FromArray(attestationObject);
     responseObject["clientDataJSON"] = browserMessageBuilder()->getBase64FromJson(clientDataJson);
+    responseObject["clientExtensionResults"] = credentialCreationOptions["clientExtensionResults"];
 
     // PublicKeyCredential
     QJsonObject publicKeyCredential;
@@ -142,6 +143,7 @@ QJsonObject BrowserPasskeys::buildGetPublicKeyCredential(const QJsonObject& asse
     QJsonObject responseObject;
     responseObject["authenticatorData"] = browserMessageBuilder()->getBase64FromArray(authenticatorData);
     responseObject["clientDataJSON"] = browserMessageBuilder()->getBase64FromJson(clientDataJson);
+    responseObject["clientExtensionResults"] = assertionOptions["clientExtensionResults"];
     responseObject["signature"] = browserMessageBuilder()->getBase64FromArray(signature);
     responseObject["userHandle"] = userHandle;
 
diff --git a/src/browser/BrowserPasskeysClient.cpp b/src/browser/BrowserPasskeysClient.cpp
index 15c5ffae2..64857a72a 100644
--- a/src/browser/BrowserPasskeysClient.cpp
+++ b/src/browser/BrowserPasskeysClient.cpp
@@ -101,13 +101,14 @@ int BrowserPasskeysClient::getCredentialCreationOptions(const QJsonObject& publi
     // Extensions
     auto extensionObject = publicKeyOptions["extensions"].toObject();
     const auto extensionData = passkeyUtils()->buildExtensionData(extensionObject);
-    const auto extensions = browserMessageBuilder()->getBase64FromArray(extensionData);
+    const auto extensions = browserMessageBuilder()->getBase64FromArray(extensionData.extensionData);
 
     // Construct the final object
     QJsonObject credentialCreationOptions;
     credentialCreationOptions["attestation"] = attestation; // Set this, even if only "none" is supported
     credentialCreationOptions["authenticatorAttachment"] = authenticatorAttachment;
     credentialCreationOptions["clientDataJSON"] = passkeyUtils()->buildClientDataJson(publicKeyOptions, origin, false);
+    credentialCreationOptions["clientExtensionResults"] = extensionData.extensionObject;
     credentialCreationOptions["credTypesAndPubKeyAlgs"] = pubKeyCredParams;
     credentialCreationOptions["excludeCredentials"] = publicKeyOptions["excludeCredentials"];
     credentialCreationOptions["extensions"] = extensions;
@@ -148,7 +149,7 @@ int BrowserPasskeysClient::getAssertionOptions(const QJsonObject& publicKeyOptio
     // Extensions
     auto extensionObject = publicKeyOptions["extensions"].toObject();
     const auto extensionData = passkeyUtils()->buildExtensionData(extensionObject);
-    const auto extensions = browserMessageBuilder()->getBase64FromArray(extensionData);
+    const auto extensions = browserMessageBuilder()->getBase64FromArray(extensionData.extensionData);
 
     // clientDataJson
     const auto clientDataJson = passkeyUtils()->buildClientDataJson(publicKeyOptions, origin, true);
@@ -163,6 +164,7 @@ int BrowserPasskeysClient::getAssertionOptions(const QJsonObject& publicKeyOptio
     QJsonObject assertionOptions;
     assertionOptions["allowCredentials"] = publicKeyOptions["allowCredentials"];
     assertionOptions["clientDataJson"] = clientDataJson;
+    assertionOptions["clientExtensionResults"] = extensionData.extensionObject;
     assertionOptions["extensions"] = extensions;
     assertionOptions["rpId"] = rpId;
     assertionOptions["userPresence"] = true;
diff --git a/src/browser/PasskeyUtils.cpp b/src/browser/PasskeyUtils.cpp
index a40caa1e4..fac9af09b 100644
--- a/src/browser/PasskeyUtils.cpp
+++ b/src/browser/PasskeyUtils.cpp
@@ -305,9 +305,8 @@ bool PasskeyUtils::isUserVerificationRequired(const QJsonObject& authenticatorSe
                && BrowserPasskeys::SUPPORT_USER_VERIFICATION);
 }
 
-QByteArray PasskeyUtils::buildExtensionData(QJsonObject& extensionObject) const
+ExtensionResult PasskeyUtils::buildExtensionData(QJsonObject& extensionObject) const
 {
-    // Only supports "credProps" and "uvm" for now
     const QStringList allowedKeys = {"credProps", "uvm"};
 
     // Remove unsupported keys
@@ -317,9 +316,36 @@ QByteArray PasskeyUtils::buildExtensionData(QJsonObject& extensionObject) const
         }
     }
 
+    // Create response object
+    QJsonObject extensionJSON;
+
+    // https://w3c.github.io/webauthn/#sctn-authenticator-credential-properties-extension
+    if (extensionObject.contains("credProps") && extensionObject["credProps"].toBool()) {
+        extensionJSON["credProps"] = QJsonObject({{"rk", true}});
+    }
+
+    // https://w3c.github.io/webauthn/#sctn-uvm-extension
+    if (extensionObject.contains("uvm") && extensionObject["uvm"].toBool()) {
+        QJsonArray uvmResponse;
+        QJsonArray uvmArray = {
+            1, // userVerificationMethod (USER_VERIFY_PRESENCE_INTERNAL "presence_internal", 0x00000001)
+            1, // keyProtectionType (KEY_PROTECTION_SOFTWARE "software", 0x0001)
+            1, // matcherProtectionType (MATCHER_PROTECTION_SOFTWARE "software", 0x0001)
+        };
+        uvmResponse.append(uvmArray);
+        extensionJSON["uvm"] = uvmResponse;
+    }
+
+    if (extensionJSON.isEmpty()) {
+        return {};
+    }
+
     auto extensionData = m_browserCbor.cborEncodeExtensionData(extensionObject);
     if (!extensionData.isEmpty()) {
-        return extensionData;
+        ExtensionResult result;
+        result.extensionData = extensionData;
+        result.extensionObject = extensionJSON;
+        return result;
     }
 
     return {};
diff --git a/src/browser/PasskeyUtils.h b/src/browser/PasskeyUtils.h
index 0ac689ae6..ec8e47668 100644
--- a/src/browser/PasskeyUtils.h
+++ b/src/browser/PasskeyUtils.h
@@ -30,6 +30,12 @@
 #define DEFAULT_DISCOURAGED_TIMEOUT 120000
 #define PASSKEYS_SUCCESS 0
 
+struct ExtensionResult
+{
+    QByteArray extensionData;
+    QJsonObject extensionObject;
+};
+
 class PasskeyUtils : public QObject
 {
     Q_OBJECT
@@ -51,7 +57,7 @@ public:
     bool isResidentKeyRequired(const QJsonObject& authenticatorSelection) const;
     bool isUserVerificationRequired(const QJsonObject& authenticatorSelection) const;
     bool isOriginAllowedWithLocalhost(bool allowLocalhostWithPasskeys, const QString& origin) const;
-    QByteArray buildExtensionData(QJsonObject& extensionObject) const;
+    ExtensionResult buildExtensionData(QJsonObject& extensionObject) const;
     QJsonObject buildClientDataJson(const QJsonObject& publicKey, const QString& origin, bool get) const;
     QStringList getAllowedCredentialsFromAssertionOptions(const QJsonObject& assertionOptions) const;
     QString getCredentialIdFromEntry(const Entry* entry) const;
diff --git a/tests/TestPasskeys.cpp b/tests/TestPasskeys.cpp
index 160087b6e..1618dce28 100644
--- a/tests/TestPasskeys.cpp
+++ b/tests/TestPasskeys.cpp
@@ -459,9 +459,9 @@ void TestPasskeys::testExtensions()
     auto result = passkeyUtils()->buildExtensionData(extensions);
 
     BrowserCbor cbor;
-    auto extensionJson = cbor.getJsonFromCborData(result);
-    auto uvmArray = extensionJson["uvm"].toArray();
-    QCOMPARE(extensionJson["credProps"].toObject()["rk"].toBool(), true);
+    auto extensionJson = cbor.getJsonFromCborData(result.extensionData);
+    auto uvmArray = result.extensionObject["uvm"].toArray();
+    QCOMPARE(result.extensionObject["credProps"].toObject()["rk"].toBool(), true);
     QCOMPARE(uvmArray.size(), 1);
     QCOMPARE(uvmArray.first().toArray().size(), 3);
 
@@ -470,10 +470,10 @@ void TestPasskeys::testExtensions()
     auto partialData = passkeyUtils()->buildExtensionData(partial);
     auto faultyData = passkeyUtils()->buildExtensionData(faulty);
 
-    auto partialJson = cbor.getJsonFromCborData(partialData);
+    auto partialJson = cbor.getJsonFromCborData(partialData.extensionData);
     QCOMPARE(partialJson["uvm"].toArray().size(), 1);
 
-    auto faultyJson = cbor.getJsonFromCborData(faultyData);
+    auto faultyJson = cbor.getJsonFromCborData(faultyData.extensionData);
     QCOMPARE(faultyJson.size(), 0);
 }