--- a/browser/extensions/onboarding/content/onboarding-tour-agent.js
+++ b/browser/extensions/onboarding/content/onboarding-tour-agent.js
@@ -10,31 +10,43 @@ document.getElementById("onboarding-over
                         .addEventListener("click", evt => {
   switch (evt.target.id) {
     case "onboarding-tour-addons-button":
       Mozilla.UITour.showHighlight("addons");
       break;
     case "onboarding-tour-customize-button":
       Mozilla.UITour.showHighlight("customize");
       break;
-   case "onboarding-tour-default-browser-button":
-      Mozilla.UITour.setConfiguration("defaultBrowser");
+    case "onboarding-tour-default-browser-button":
+      Mozilla.UITour.getConfiguration("appinfo", (config) => {
+        let isDefaultBrowser = config.defaultBrowser;
+        let btn = document.getElementById("onboarding-tour-default-browser-button");
+        let msg = document.getElementById("onboarding-tour-is-default-browser-msg");
+        if (isDefaultBrowser) {
+          btn.classList.add("onboarding-hidden");
+          msg.classList.remove("onboarding-hidden");
+        } else {
+          btn.disabled = true;
+          Mozilla.UITour.setConfiguration("defaultBrowser");
+        }
+      });
       break;
     case "onboarding-tour-private-browsing-button":
       Mozilla.UITour.showHighlight("privateWindow");
       break;
     case "onboarding-tour-search-button":
       Mozilla.UITour.openSearchPanel(() => {});
       break;
     case "onboarding-tour-sync-button":
       let emailInput = document.getElementById("onboarding-tour-sync-email-input");
       Mozilla.UITour.showFirefoxAccounts(null, emailInput.value);
       break;
     case "onboarding-overlay":
     case "onboarding-overlay-close-btn":
       // Dismiss any highlights if a user tries to close the dialog.
       Mozilla.UITour.hideHighlight();
+      break;
   }
   // Dismiss any highlights if a user tries to change to other tours.
   if (evt.target.classList.contains("onboarding-tour-item")) {
     Mozilla.UITour.hideHighlight();
   }
 });

--- a/browser/extensions/onboarding/content/onboarding.css
+++ b/browser/extensions/onboarding/content/onboarding.css
@@ -28,17 +28,18 @@
   height: 29px;
   position: absolute;
   cursor: pointer;
   top: 30px;
   offset-inline-start: 30px;
   background: url("img/overlay-icon.svg") no-repeat;
 }
 
-#onboarding-overlay-dialog {
+#onboarding-overlay-dialog,
+.onboarding-hidden {
   display: none;
 }
 
 #onboarding-overlay-close-btn,
 #onboarding-notification-close-btn {
   position: absolute;
   top: 15px;
   offset-inline-end: 15px;
@@ -144,16 +145,26 @@
   padding-inline-start: 29px;
 }
 
 #onboarding-tour-list > li.onboarding-active,
 #onboarding-tour-list > li:hover {
   color: #0A84FF;
 }
 
+/* Default browser tour */
+#onboarding-tour-is-default-browser-msg {
+  font-size: 16px;
+  line-height: 21px;
+  float: inline-end;
+  margin-inline-end: 26px;
+  margin-top: -32px;
+  text-align: center;
+}
+
 /* Sync tour */
 #onboarding-tour-sync-page form {
   text-align: center;
 }
 
 #onboarding-tour-sync-page form > h3 {
   text-align: center;
   margin: 0;
@@ -256,23 +267,23 @@
   border: none;
   border-radius: 0;
   color: #fff;
   float: inline-end;
   margin-inline-end: 26px;
   margin-top: -32px;
 }
 
-.onboarding-tour-action-button:hover:not([disabled="true"]) ,
+.onboarding-tour-action-button:hover:not([disabled]) ,
 #onboarding-notification-action-btn:hover {
   background: #0060df;
   cursor: pointer;
 }
 
-.onboarding-tour-action-button:active:not([disabled="true"]),
+.onboarding-tour-action-button:active:not([disabled]),
 #onboarding-notification-action-btn:active  {
   background: #003EAA;
 }
 
 .onboarding-tour-action-button:disabled {
   opacity: 0.5;
 }
 

--- a/browser/extensions/onboarding/content/onboarding.js
+++ b/browser/extensions/onboarding/content/onboarding.js
@@ -155,31 +155,34 @@ var onboardingTourset = {
     tourNameId: "onboarding.tour-default-browser",
     getNotificationStrings(bundle) {
       return {
         title: bundle.formatStringFromName("onboarding.notification.onboarding-tour-default-browser.title", [BRAND_SHORT_NAME], 1),
         message: bundle.formatStringFromName("onboarding.notification.onboarding-tour-default-browser.message", [BRAND_SHORT_NAME], 1),
         button: bundle.GetStringFromName("onboarding.button.learnMore"),
       };
     },
-    getPage(win) {
+    getPage(win, bundle) {
       let div = win.document.createElement("div");
       let defaultBrowserButtonId = win.matchMedia("(-moz-os-version: windows-win7)").matches ?
         "onboarding.tour-default-browser.win7.button" : "onboarding.tour-default-browser.button";
+      let isDefaultMessage = bundle.GetStringFromName("onboarding.tour-default-browser.is-default.message");
+      let isDefault2ndMessage = bundle.formatStringFromName("onboarding.tour-default-browser.is-default.2nd-message", [BRAND_SHORT_NAME], 1);
       // eslint-disable-next-line no-unsanitized/property
       div.innerHTML = `
         <section class="onboarding-tour-description">
           <h1 data-l10n-id="onboarding.tour-default-browser.title2"></h1>
           <p data-l10n-id="onboarding.tour-default-browser.description2"></p>
         </section>
         <section class="onboarding-tour-content">
           <img src="resource://onboarding/img/figure_default.svg" />
         </section>
         <aside class="onboarding-tour-button-container">
           <button id="onboarding-tour-default-browser-button" class="onboarding-tour-action-button" data-l10n-id="${defaultBrowserButtonId}"></button>
+          <div id="onboarding-tour-is-default-browser-msg" class="onboarding-hidden">${isDefaultMessage}<br/>${isDefault2ndMessage}</div>
         </aside>
       `;
       return div;
     },
   },
   "sync": {
     id: "onboarding-tour-sync",
     tourNameId: "onboarding.tour-sync2",

--- a/browser/extensions/onboarding/locales/en-US/onboarding.properties
+++ b/browser/extensions/onboarding/locales/en-US/onboarding.properties
@@ -51,16 +51,20 @@ onboarding.tour-default-browser=Default 
 # LOCALIZATION NOTE(onboarding.tour-default-browser.title2): This string will be used in the default browser tour title. %S is brandShortName
 onboarding.tour-default-browser.title2=Make %S your go-to browser.
 # LOCALIZATION NOTE(onboarding.tour-default-browser.description2): This string will be used in the default browser tour description. %1$S is brandShortName
 onboarding.tour-default-browser.description2=Love %1$S? Set it as your default browser. Open a link from another application, and %1$S will be there for you.
 # LOCALIZATION NOTE(onboarding.tour-default-browser.button): Label for a button to open the OS default browser settings where it's not possible to set the default browser directly. (OSX, Linux, Windows 8 and higher)
 onboarding.tour-default-browser.button=Open Default Browser Settings
 # LOCALIZATION NOTE(onboarding.tour-default-browser.win7.button): Label for a button to directly set the default browser (Windows 7). %S is brandShortName
 onboarding.tour-default-browser.win7.button=Make %S Your Default Browser
+# LOCALIZATION NOTE(onboarding.tour-default-browser.is-default.message): Label displayed when Firefox is already set as default browser. followed on a new line by "tour-default-browser.is-default.2nd-message".
+onboarding.tour-default-browser.is-default.message=You’ve got this!
+# LOCALIZATION NOTE(onboarding.tour-default-browser.is-default.2nd-message): Label displayed when Firefox is already set as default browser. %S is brandShortName
+onboarding.tour-default-browser.is-default.2nd-message=%S is already your default browser.
 # LOCALIZATION NOTE(onboarding.notification.onboarding-tour-default-browser.title): This string will be used in the notification message for the default browser tour. %S is brandShortName.
 onboarding.notification.onboarding-tour-default-browser.title=Make %S your go-to browser.
 # LOCALIZATION NOTE(onboarding.notification.onboarding-tour-default-browser.message): %1$S is brandShortName
 onboarding.notification.onboarding-tour-default-browser.message=It doesn’t take much to get the most from %1$S. Just set %1$S as your default browser and put control, customization, and protection on autopilot.
 
 onboarding.tour-sync2=Sync
 onboarding.tour-sync.title2=Pick up where you left off.
 onboarding.tour-sync.description2=Sync makes it easy to access bookmarks, passwords, and even open tabs on all your devices. Sync also gives you control of the types of information you want, and don’t want, to share.