diff --git a/docs/documentation/upgrading/topics/keycloak/changes-22_0_0.adoc b/docs/documentation/upgrading/topics/keycloak/changes-22_0_0.adoc
index 7f2a012dc6..a866bafcf7 100644
--- a/docs/documentation/upgrading/topics/keycloak/changes-22_0_0.adoc
+++ b/docs/documentation/upgrading/topics/keycloak/changes-22_0_0.adoc
@@ -49,3 +49,19 @@ try {
   alert('failed to initialize');
 }
 ```
+
+= Keycloak JS adapter must be instanciated with the `new` operator
+
+Historically it has been possible to create an instance of the Keycloak JS adapter by calling the `Keycloak()` function directly:
+
+```js
+const keycloak = Keycloak();
+```
+
+To align this with modern conventions in the JavaScript world it has been possible to use the https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/new[`new` operator] to create an instance instead:
+
+```js
+const keycloak = new Keycloak();
+```
+
+The function-style constructor has been deprecated for a while, but starting this version we will actively log a deprecation message when it used. This style of constructor will be removed in a future version so make sure to migrate your code to use the `new` operator.
diff --git a/examples/js-console/src/main/webapp/index.html b/examples/js-console/src/main/webapp/index.html
index 840e89b26c..ca780281fb 100644
--- a/examples/js-console/src/main/webapp/index.html
+++ b/examples/js-console/src/main/webapp/index.html
@@ -130,7 +130,7 @@
         document.getElementById('events').innerHTML = new Date().toLocaleString() + "\t" + event + "\n" + e;
     }
 
-    var keycloak = Keycloak();
+    var keycloak = new Keycloak();
 
     keycloak.onAuthSuccess = function () {
         event('Auth Success');
diff --git a/js/libs/keycloak-js/src/keycloak.js b/js/libs/keycloak-js/src/keycloak.js
index 3b1af3c008..42a5d60264 100755
--- a/js/libs/keycloak-js/src/keycloak.js
+++ b/js/libs/keycloak-js/src/keycloak.js
@@ -21,8 +21,18 @@ if (typeof Promise === 'undefined') {
     throw Error('Keycloak requires an environment that supports Promises. Make sure that you include the appropriate polyfill.');
 }
 
+var loggedConstructorDeprecation = false;
+
+function logConstructorDeprecation() {
+    if (!loggedConstructorDeprecation) {
+        loggedConstructorDeprecation = true;
+        console.warn('[KEYCLOAK] Instantiation using the `Keycloak` function has been deprecated and support will be removed in future versions. Use the `new` operator to create an instance instead.');
+    }
+}
+
 function Keycloak (config) {
     if (!(this instanceof Keycloak)) {
+        logConstructorDeprecation();
         return new Keycloak(config);
     }
 
diff --git a/testsuite/integration-arquillian/tests/base/src/main/java/org/keycloak/testsuite/util/javascript/JavascriptTestExecutor.java b/testsuite/integration-arquillian/tests/base/src/main/java/org/keycloak/testsuite/util/javascript/JavascriptTestExecutor.java
index 3b1db81fb6..92e1ccab02 100644
--- a/testsuite/integration-arquillian/tests/base/src/main/java/org/keycloak/testsuite/util/javascript/JavascriptTestExecutor.java
+++ b/testsuite/integration-arquillian/tests/base/src/main/java/org/keycloak/testsuite/util/javascript/JavascriptTestExecutor.java
@@ -167,10 +167,10 @@ public class JavascriptTestExecutor {
         jsExecutor.executeScript("console.warn = event;");
 
         if (argumentsBuilder == null) {
-            jsExecutor.executeScript("window.keycloak = Keycloak();");
+            jsExecutor.executeScript("window.keycloak = new Keycloak();");
         } else {
             String configArguments = argumentsBuilder.build();
-            jsExecutor.executeScript("window.keycloak = Keycloak(" + configArguments + ");");
+            jsExecutor.executeScript("window.keycloak = new Keycloak(" + configArguments + ");");
         }
 
         jsExecutor.executeScript("window.keycloak.onAuthSuccess = function () {event('Auth Success')};"); // event function is declared in index.html
diff --git a/themes/src/main/resources/theme/keycloak.v2/account/index.ftl b/themes/src/main/resources/theme/keycloak.v2/account/index.ftl
index 212b38ca85..84c45c4b14 100644
--- a/themes/src/main/resources/theme/keycloak.v2/account/index.ftl
+++ b/themes/src/main/resources/theme/keycloak.v2/account/index.ftl
@@ -124,7 +124,7 @@
     <body>
 
         <script>
-            var keycloak = Keycloak({
+            var keycloak = new Keycloak({
                 authServerUrl: authUrl,
                 realm: realm,
                 clientId: 'account-console'