diff --git a/browser/components/originattributes/test/browser/browser_favicon_firstParty.js b/browser/components/originattributes/test/browser/browser_favicon_firstParty.js
index a6ec99e0d722..cd9867eebee6 100644
--- a/browser/components/originattributes/test/browser/browser_favicon_firstParty.js
+++ b/browser/components/originattributes/test/browser/browser_favicon_firstParty.js
@@ -42,8 +42,6 @@ const ICON_DATA =
   "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYAAABzenr0AAABH0lEQVRYw2P8////f4YBBEwMAwxGHcBCUMX/91DGOSj/BpT/DkpzQChGBSjfBErLQsVZhmoI/L8LpRdD6X1QietQGhYy7FB5aAgwmkLpBKi4BZTPMThDgBGjHIDF+f9mKD0fKvGBRKNdoF7sgPL1saaJwZgGDkJ9vpZMn8PAHqg5G9FyifBgD4H/W9HyOWrU/f+DIzHhkoeZxxgzZEIAVtJ9RxX+Q6DAxCmP3byhXxkxshAs5odqbcioAY3UC1CBLyTGOTqAmsfAOWRCwBvqxV0oIUB2OQAzDy3/D+a6wB7q8mCU2vD/nw94GziYIQOtDRn9oXz+IZMGBKGMbCjNh9Ii+v8HR4uIAUeLiEEbb9twELaIRlqrmHG0bzjiHQAA1LVfww8jwM4AAAAASUVORK5CYII=";
 
 let systemPrincipal = Services.scriptSecurityManager.getSystemPrincipal();
-let makeURI = ChromeUtils.import("resource://gre/modules/BrowserUtils.jsm", {})
-  .BrowserUtils.makeURI;
 
 function clearAllImageCaches() {
   let tools = SpecialPowers.Cc["@mozilla.org/image/tools;1"].getService(
@@ -244,8 +242,8 @@ function assertIconIsData(item) {
 }
 
 async function doTest(aTestPage, aExpectedCookies, aFaviconURL) {
-  let firstPageURI = makeURI(TEST_SITE_ONE + aTestPage);
-  let secondPageURI = makeURI(TEST_SITE_TWO + aTestPage);
+  let firstPageURI = Services.io.newURI(TEST_SITE_ONE + aTestPage);
+  let secondPageURI = Services.io.newURI(TEST_SITE_TWO + aTestPage);
 
   // Start to observe the event of that favicon has been fully loaded.
   let promiseFaviconLoaded = waitOnFaviconLoaded(aFaviconURL);
diff --git a/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_favicon.js b/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_favicon.js
index c0e671ce34ed..b455a60fab5d 100644
--- a/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_favicon.js
+++ b/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_favicon.js
@@ -15,8 +15,6 @@ const FAVICON_URI = TEST_SITE + TEST_DIRECTORY + "file_favicon.png";
 const FAVICON_CACHE_URI = TEST_CACHE_SITE + TEST_DIRECTORY + "file_favicon.png";
 
 let systemPrincipal = Services.scriptSecurityManager.getSystemPrincipal();
-let makeURI = ChromeUtils.import("resource://gre/modules/BrowserUtils.jsm", {})
-  .BrowserUtils.makeURI;
 
 function clearAllImageCaches() {
   let tools = SpecialPowers.Cc["@mozilla.org/image/tools;1"].getService(
@@ -205,7 +203,7 @@ add_task(async function test_favicon_privateBrowsing() {
   let privateWindow = await BrowserTestUtils.openNewBrowserWindow({
     private: true,
   });
-  let pageURI = makeURI(TEST_PAGE);
+  let pageURI = Services.io.newURI(TEST_PAGE);
 
   // Generate two random cookies for non-private window and private window
   // respectively.
diff --git a/caps/tests/mochitest/browser_checkloaduri.js b/caps/tests/mochitest/browser_checkloaduri.js
index 4607c802288e..3f114427335d 100644
--- a/caps/tests/mochitest/browser_checkloaduri.js
+++ b/caps/tests/mochitest/browser_checkloaduri.js
@@ -254,7 +254,7 @@ function testURL(
   let threw = false;
   let targetURI;
   try {
-    targetURI = makeURI(target);
+    targetURI = Services.io.newURI(target);
   } catch (ex) {
     ok(
       !canCreate,
@@ -300,7 +300,7 @@ add_task(async function() {
     if (sourceString.startsWith("about:test-chrome-privs")) {
       source = ssm.getSystemPrincipal();
     } else {
-      source = ssm.createContentPrincipal(makeURI(sourceString), {});
+      source = ssm.createContentPrincipal(Services.io.newURI(sourceString), {});
     }
     for (let [
       target,
@@ -341,10 +341,6 @@ add_task(async function() {
       // eslint-disable-next-line no-shadow
       let baseFlags = ssm.STANDARD | ssm.DONT_REPORT_ERRORS;
       // eslint-disable-next-line no-unused-vars
-      let makeURI = ChromeUtils.import(
-        "resource://gre/modules/BrowserUtils.jsm",
-        {}
-      ).BrowserUtils.makeURI;
       let b = new content.Blob(["I am a blob"]);
       let contentBlobURI = content.URL.createObjectURL(b);
       let contentPrincipal = content.document.nodePrincipal;
diff --git a/dom/security/test/general/test_bug1277803.xhtml b/dom/security/test/general/test_bug1277803.xhtml
index 482dd6b916ec..43afb1f1a355 100644
--- a/dom/security/test/general/test_bug1277803.xhtml
+++ b/dom/security/test/general/test_bug1277803.xhtml
@@ -15,46 +15,41 @@
 
   <script type="application/javascript"><![CDATA[
     SimpleTest.requestCompleteLog();
-    let makeURI = ChromeUtils.import("resource://gre/modules/BrowserUtils.jsm", {}).BrowserUtils.makeURI;
 
     const BASE_URI = "http://mochi.test:8888/chrome/dom/security/test/general/";
     const FAVICON_URI = BASE_URI + "favicon_bug1277803.ico";
     const LOADING_URI = BASE_URI + "bug1277803.html";
     let testWindow; //will be used to trigger favicon load
 
-    let securityManager = Cc["@mozilla.org/scriptsecuritymanager;1"].
-                          getService(Ci.nsIScriptSecurityManager);
-    let expectedPrincipal = securityManager.createContentPrincipal(makeURI(LOADING_URI), {});
-    let systemPrincipal = Cc["@mozilla.org/systemprincipal;1"].createInstance();
+    const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+    let expectedPrincipal = Services.scriptSecurityManager
+        .createContentPrincipal(Services.io.newURI(LOADING_URI), {});
+    let systemPrincipal = Services.scriptSecurityManager.getSystemPrincipal();
 
     function runTest() {
       // Register our observer to intercept favicon requests.
-      let os = Cc["@mozilla.org/observer-service;1"].
-               getService(Ci.nsIObserverService);
-      let observer = {
-        observe: function(aSubject, aTopic, aData)
-        {
-          // Make sure this is a favicon request.
-          let httpChannel = aSubject.QueryInterface(Ci.nsIHttpChannel);
-          if (FAVICON_URI != httpChannel.URI.spec) {
-            return;
-          }
-
-          // Ensure the topic is the one we set an observer for.
-          is(aTopic, "http-on-modify-request", "Expected observer topic");
-
-          // Check for the correct loadingPrincipal, triggeringPrincipal.
-          let triggeringPrincipal = httpChannel.loadInfo.triggeringPrincipal;
-          let loadingPrincipal = httpChannel.loadInfo.loadingPrincipal;
-
-          ok(loadingPrincipal.equals(expectedPrincipal), "Should be loading with the expected principal.");
-          ok(triggeringPrincipal.equals(expectedPrincipal), "Should be triggered with the expected principal.");
-
-          os.removeObserver(this, "http-on-modify-request");
-          SimpleTest.finish();
+      function observer(aSubject, aTopic, aData) {
+        // Make sure this is a favicon request.
+        let httpChannel = aSubject.QueryInterface(Ci.nsIHttpChannel);
+        if (FAVICON_URI != httpChannel.URI.spec) {
+          return;
         }
+
+        // Ensure the topic is the one we set an observer for.
+        is(aTopic, "http-on-modify-request", "Expected observer topic");
+
+        // Check for the correct loadingPrincipal, triggeringPrincipal.
+        let triggeringPrincipal = httpChannel.loadInfo.triggeringPrincipal;
+        let loadingPrincipal = httpChannel.loadInfo.loadingPrincipal;
+
+        ok(loadingPrincipal.equals(expectedPrincipal), "Should be loading with the expected principal.");
+        ok(triggeringPrincipal.equals(expectedPrincipal), "Should be triggered with the expected principal.");
+
+        Services.obs.removeObserver(this, "http-on-modify-request");
+        SimpleTest.finish();
       }
-      os.addObserver(observer, "http-on-modify-request");
+      Services.obs.addObserver(observer, "http-on-modify-request");
 
       // Now that the observer is set up, trigger a favicon load with navigation
       testWindow = window.open(LOADING_URI);
diff --git a/toolkit/modules/BrowserUtils.jsm b/toolkit/modules/BrowserUtils.jsm
index bccbf0f6aa0d..593cd7c02090 100644
--- a/toolkit/modules/BrowserUtils.jsm
+++ b/toolkit/modules/BrowserUtils.jsm
@@ -193,26 +193,6 @@ var BrowserUtils = {
     );
   },
 
-  /**
-   * Constructs a new URI, using nsIIOService.
-   * @param aURL The URI spec.
-   * @param aOriginCharset The charset of the URI.
-   * @param aBaseURI Base URI to resolve aURL, or null.
-   * @return an nsIURI object based on aURL.
-   *
-   * @deprecated Use Services.io.newURI directly instead.
-   */
-  makeURI(aURL, aOriginCharset, aBaseURI) {
-    return Services.io.newURI(aURL, aOriginCharset, aBaseURI);
-  },
-
-  /**
-   * @deprecated Use Services.io.newFileURI directly instead.
-   */
-  makeFileURI(aFile) {
-    return Services.io.newFileURI(aFile);
-  },
-
   /**
    * For a given DOM element, returns its position in "screen"
    * coordinates. In a content process, the coordinates returned will
@@ -559,7 +539,7 @@ var BrowserUtils = {
       linkText = selectionStr.trim();
       if (/^(?:https?|ftp):/i.test(linkText)) {
         try {
-          url = this.makeURI(linkText);
+          url = Services.io.newURI(linkText);
         } catch (ex) {}
       } else if (/^(?:[a-z\d-]+\.)+[a-z]+$/i.test(linkText)) {
         // Check if this could be a valid url, just missing the protocol.