diff --git a/.eslintrc.js b/.eslintrc.js
index 437544739070..f05a73f512f4 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -580,7 +580,6 @@ module.exports = {
         "toolkit/components/lz4/lz4.js",
         "toolkit/components/messaging-system/**",
         "toolkit/components/mozintl/mozIntl.sys.mjs",
-        "toolkit/components/narrate/Narrator.jsm",
         "toolkit/components/nimbus/**",
         "toolkit/components/normandy/**",
         "toolkit/components/passwordmgr/**",
@@ -1267,7 +1266,6 @@ module.exports = {
         "browser/components/urlbar/tests/browser/browser_view_resultDisplay.js",
         "browser/components/urlbar/tests/browser/browser_view_resultTypes_display.js",
         "browser/components/urlbar/tests/ext/browser/browser_ext_urlbar_clearInput.js",
-        "browser/components/urlbar/tests/quicksuggest/QuickSuggestTestUtils.jsm ",
         "browser/components/urlbar/tests/quicksuggest/browser/browser_quicksuggest.js",
         "browser/components/urlbar/tests/quicksuggest/browser/browser_quicksuggest_block.js",
         "browser/components/urlbar/tests/quicksuggest/browser/browser_quicksuggest_configuration.js",
@@ -1828,7 +1826,6 @@ module.exports = {
         "dom/u2f/tests/frame_appid_facet_insecure.html",
         "dom/u2f/tests/frame_appid_facet_subdomain.html",
         "dom/url/tests/browser_download_after_revoke.js",
-        "dom/url/tests/file_url.jsm ",
         "dom/url/tests/protocol_worker.js",
         "dom/url/tests/test_unknown_url_origin.html",
         "dom/url/tests/test_url.html",
@@ -1873,7 +1870,6 @@ module.exports = {
         "image/test/browser/head.js",
         "image/test/mochitest/test_animated_gif.html",
         "image/test/mochitest/test_bug671906.html",
-        "intl/locale/tests/LangPackMatcherTestUtils.jsm ",
         "layout/base/tests/browser_disableDialogs_onbeforeunload.js",
         "layout/base/tests/browser_lazyload_page_load_telemetry_iframe.js",
         "layout/base/tests/browser_lazyload_telemetry.js",
@@ -1905,8 +1901,6 @@ module.exports = {
         "netwerk/test/browser/browser_103_preload.js",
         "netwerk/test/browser/browser_cookie_filtering_subdomain.js",
         "netwerk/test/browser/browser_test_favicon.js",
-        "netwerk/test/browser/cookie_filtering_helper.jsm",
-        "netwerk/test/browser/early_hint_preload_test_helper.jsm ",
         "netwerk/test/httpserver/httpd.js",
         "netwerk/test/mochitests/file_loadinfo_redirectchain.sjs",
         "netwerk/test/mochitests/file_testloadflags_chromescript.js",
@@ -2016,11 +2010,9 @@ module.exports = {
         "toolkit/components/httpsonlyerror/tests/browser/browser_errorpage_www_suggestion.js",
         "toolkit/components/httpsonlyerror/tests/browser/browser_exception.js",
         "toolkit/components/narrate/test/head.js",
-        "toolkit/components/normandy/test/NormandyTestUtils.jsm ",
         "toolkit/components/normandy/test/browser/browser_RecipeRunner.js",
         "toolkit/components/normandy/test/browser/browser_actions_ShowHeartbeatAction.js",
         "toolkit/components/normandy/test/browser/head.js",
-        "toolkit/components/passwordmgr/test/LoginTestUtils.jsm ",
         "toolkit/components/passwordmgr/test/browser/browser_autofill_http.js",
         "toolkit/components/passwordmgr/test/browser/browser_context_menu.js",
         "toolkit/components/passwordmgr/test/browser/browser_context_menu_iframe.js",
diff --git a/browser/components/aboutwelcome/.eslintrc.js b/browser/components/aboutwelcome/.eslintrc.js
index 98c255ab7f4d..9d17fd40c263 100644
--- a/browser/components/aboutwelcome/.eslintrc.js
+++ b/browser/components/aboutwelcome/.eslintrc.js
@@ -46,7 +46,7 @@ module.exports = {
     {
       // Use a configuration that's appropriate for modules, workers and
       // non-production files.
-      files: ["modules/*.jsm", "tests/**"],
+      files: ["tests/**"],
       rules: {
         "no-implicit-globals": "off",
       },
diff --git a/browser/components/newtab/.eslintrc.js b/browser/components/newtab/.eslintrc.js
index 7fd054e8784f..f541cdd9880f 100644
--- a/browser/components/newtab/.eslintrc.js
+++ b/browser/components/newtab/.eslintrc.js
@@ -58,7 +58,7 @@ module.exports = {
     {
       // Use a configuration that's appropriate for modules, workers and
       // non-production files.
-      files: ["*.jsm", "lib/cache.worker.js", "test/**"],
+      files: ["lib/cache.worker.js", "test/**"],
       rules: {
         "no-implicit-globals": "off",
       },
diff --git a/devtools/.eslintrc.js b/devtools/.eslintrc.js
index 7fab2039c661..2b642f6bb6f5 100644
--- a/devtools/.eslintrc.js
+++ b/devtools/.eslintrc.js
@@ -82,30 +82,6 @@ module.exports = {
         "**/test*/**/*",
       ],
     },
-    {
-      // Cu, Cc etc... are not available in most devtools modules loaded by require.
-      files: ["**"],
-      excludedFiles: [
-        // Enable the rule on JSM, test head files and some specific files.
-        "**/*.jsm",
-        "**/*.sjs",
-        "**/test/**/head.js",
-        "**/test/**/shared-head.js",
-        "client/debugger/test/mochitest/code_frame-script.js",
-        "client/responsive.html/browser/content.js",
-        "server/startup/content-process.js",
-        "server/startup/frame.js",
-        "shared/loader/base-loader.sys.mjs",
-        "shared/loader/browser-loader.js",
-        "shared/loader/worker-loader.js",
-        "startup/aboutdebugging-registration.js",
-        "startup/aboutdevtoolstoolbox-registration.js",
-        "startup/devtools-startup.js",
-      ],
-      rules: {
-        "mozilla/no-define-cc-etc": "off",
-      },
-    },
     {
       // All DevTools files should avoid relative paths.
       files: ["**"],
diff --git a/devtools/docs/contributor/contributing/eslint.md b/devtools/docs/contributor/contributing/eslint.md
index 88da9592558d..55584bf12ba0 100644
--- a/devtools/docs/contributor/contributing/eslint.md
+++ b/devtools/docs/contributor/contributing/eslint.md
@@ -153,5 +153,4 @@ This should help you write eslint-clean code:
 * When cleaning an entire file or folder from ESLint errors, do not forget to remove the corresponding entry from the `.eslintignore` file.
 * When writing new code, from scratch, please make it ESLint compliant from the start. This is a lot easier than having to revisit it later.
 * ESLint also runs on `<script>` tags in HTML files, so if you create new HTML test files for mochitests for example, make sure that JavaScript code in those files is free of ESLint errors.
-* Depending on how a dependency is loaded into a file, the symbols this dependency exports might not be considered as defined by ESLint. For instance, using `Cu.import("some.jsm")` doesn't explicitly say which symbols are now available in the scope of the file, and so using those symbols will be consider by ESLint as using undefined variables. When this happens, please avoid using the `/* globals ... */` ESLint comment (which tells it that these variables are defined). Instead, please use `/* import-globals-from relative/path/to/file.js */`. This way, you won't have a list of variables to maintain manually, the globals are going to be imported dynamically instead.
 * In test files (xpcshell and mochitest), all globals from the corresponding `head.js` file are imported automatically, so you don't need to define them using a `/* globals ... */` comment or a `/* import-globals-from head.js */` comment.
diff --git a/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/import-headjs-globals.rst b/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/import-headjs-globals.rst
index df8ef813008b..51ec8eeb6291 100644
--- a/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/import-headjs-globals.rst
+++ b/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/import-headjs-globals.rst
@@ -19,7 +19,6 @@ If path does not exist because it is generated e.g.
 
 The following patterns are supported:
 
--  ``Cu.import("resource://devtools/client/shared/widgets/ViewHelpers.jsm");``
 -  ``loader.lazyRequireGetter(this, "name2"``
 -  ``loader.lazyServiceGetter(this, "name3"``
 -  ``loader.lazyGetter(this, "toolboxStrings"``
diff --git a/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/reject-mixing-eager-and-lazy.rst b/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/reject-mixing-eager-and-lazy.rst
index 51524f4e1456..1b7c165036c0 100644
--- a/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/reject-mixing-eager-and-lazy.rst
+++ b/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/reject-mixing-eager-and-lazy.rst
@@ -9,9 +9,10 @@ Examples of incorrect code for this rule:
 
 .. code-block:: js
 
-    const { SomeProp } = ChromeUtils.import("resource://gre/modules/Foo.jsm");
-    ChromeUtils.defineLazyModuleGetters(lazy, {
-      OtherProp: "resource://gre/modules/Foo.jsm",
+    const { SomeProp } =
+      ChromeUtils.importESModule("resource://gre/modules/Foo.sys.mjs");
+    ChromeUtils.defineESModuleGetters(lazy, {
+      OtherProp: "resource://gre/modules/Foo.sys.mjs",
     });
 
 Examples of correct code for this rule:
@@ -19,4 +20,6 @@ Examples of correct code for this rule:
 
 .. code-block:: js
 
-    const { SomeProp, OtherProp } = ChromeUtils.import("resource://gre/modules/Foo.jsm");
+    const { SomeProp, OtherProp } = ChromeUtils.importESModule(
+      "resource://gre/modules/Foo.sys.mjs"
+    );
diff --git a/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/reject-relative-requires.rst b/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/reject-relative-requires.rst
index 4387041b26e1..c3ec0cfed8f0 100644
--- a/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/reject-relative-requires.rst
+++ b/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/reject-relative-requires.rst
@@ -18,5 +18,5 @@ Examples of correct code for this rule:
 .. code-block:: js
 
     require("devtools/absolute/path")
-    require("resource://gre/modules/SomeModule.jsm")
+    require("resource://gre/modules/SomeModule.sys.mjs")
     loader.lazyRequireGetter(this, "path", "devtools/absolute/path", true)
diff --git a/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/valid-lazy.rst b/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/valid-lazy.rst
index a7edeeb5fc3a..e7f6706d5b07 100644
--- a/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/valid-lazy.rst
+++ b/docs/code-quality/lint/linters/eslint-plugin-mozilla/rules/valid-lazy.rst
@@ -19,10 +19,10 @@ Examples of incorrect code for this rule:
 .. code-block:: js
 
     const lazy = {};
-    ChromeUtils.defineLazyGetter(lazy, "foo", "foo.jsm");
+    ChromeUtils.defineESModuleGetters(lazy, { foo: "foo.sys.mjs"});
 
     // Duplicate symbol foo being added to lazy.
-    ChromeUtils.defineLazyGetter(lazy, "foo", "foo1.jsm");
+    ChromeUtils.defineLazyGetter(lazy, "foo", () => {});
     if (x) {
       lazy.foo3.bar();
     }
@@ -31,12 +31,12 @@ Examples of incorrect code for this rule:
 
     const lazy = {};
     // Unused lazy property foo
-    ChromeUtils.defineLazyGetter(lazy, "foo", "foo.jsm");
+    ChromeUtils.defineESModuleGetters(lazy, { foo: "foo.sys.mjs"});
 
 .. code-block:: js
 
     const lazy = {};
-    ChromeUtils.defineLazyGetter(lazy, "foo", "foo.jsm");
+    ChromeUtils.defineESModuleGetters(lazy, { foo: "foo.sys.mjs"});
     // Used at top-level unconditionally.
     lazy.foo.bar();
 
@@ -47,7 +47,7 @@ Examples of correct code for this rule:
 
     const lazy = {};
     ChromeUtils.defineLazyGetter(lazy, "foo1", () => {});
-    XPCOMUtils.defineLazyModuleGetters(lazy, { foo2: "foo2.jsm" });
+    ChromeUtils.defineESModuleGetters(lazy, { foo2: "foo2.sys.mjs"});
 
     if (x) {
       lazy.foo1.bar();
diff --git a/services/sync/tests/tps/.eslintrc.js b/services/sync/tests/tps/.eslintrc.js
index 182e87933b9d..63c834493480 100644
--- a/services/sync/tests/tps/.eslintrc.js
+++ b/services/sync/tests/tps/.eslintrc.js
@@ -2,7 +2,7 @@
 
 module.exports = {
   globals: {
-    // Injected into tests via tps.jsm
+    // Injected into tests via tps.sys.mjs
     Addons: false,
     Addresses: false,
     Bookmarks: false,
diff --git a/toolkit/components/extensions/.eslintrc.js b/toolkit/components/extensions/.eslintrc.js
index 3c0b52c1d501..8cc2d2a16f7d 100644
--- a/toolkit/components/extensions/.eslintrc.js
+++ b/toolkit/components/extensions/.eslintrc.js
@@ -6,7 +6,7 @@
 
 module.exports = {
   globals: {
-    // These are defined in the WebExtension script scopes by ExtensionCommon.jsm
+    // These are defined in the WebExtension script scopes by ExtensionCommon.sys.mjs
     Cc: true,
     Ci: true,
     Cr: true,
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js
index 30b230c06abe..c4d28594b59a 100644
--- a/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js
@@ -50,7 +50,7 @@ module.exports = {
       // environment for them.
       env: {
         browser: false,
-        "mozilla/jsm": true,
+        "mozilla/sysmjs": true,
       },
       files: ["**/*.sys.mjs", "**/*.jsm"],
       rules: {
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/environments/jsm.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/environments/sysmjs.js
similarity index 70%
rename from tools/lint/eslint/eslint-plugin-mozilla/lib/environments/jsm.js
rename to tools/lint/eslint/eslint-plugin-mozilla/lib/environments/sysmjs.js
index 30d8e0eb9c27..03fe80e5c4b4 100644
--- a/tools/lint/eslint/eslint-plugin-mozilla/lib/environments/jsm.js
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/environments/sysmjs.js
@@ -1,5 +1,5 @@
 /**
- * @fileoverview Defines the environment for jsm files.
+ * @fileoverview Defines the environment for sys module files.
  *
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -10,7 +10,7 @@
 
 module.exports = {
   globals: {
-    // These globals are hard-coded and available in .jsm scopes.
+    // These globals are hard-coded and available in .sys.mjs scopes.
     // https://searchfox.org/mozilla-central/rev/dcb0cfb66e4ed3b9c7fbef1e80572426ff5f3c3a/js/xpconnect/loader/mozJSModuleLoader.cpp#222-223
     // Although `debug` is allowed for jsm files, this is non-standard and something
     // we don't want to allow in mjs files. Hence it is not included here.
@@ -18,8 +18,8 @@ module.exports = {
     btoa: false,
     dump: false,
     // The WebAssembly global is available in most (if not all) contexts where
-    // JS can run. It's definitely available in JSMs. So even if this is not
-    // the perfect place to add it, it's not wrong, and we can move it later.
+    // JS can run. It's definitely available in system modules. So even if this
+    // is not the perfect place to add it, it's not wrong, and we can move it later.
     WebAssembly: false,
   },
 };
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/index.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/index.js
index ddbff1dc64c4..5b39cf0f7f36 100644
--- a/tools/lint/eslint/eslint-plugin-mozilla/lib/index.js
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/index.js
@@ -27,7 +27,7 @@ module.exports = {
     "chrome-script": require("../lib/environments/chrome-script.js"),
     "chrome-worker": require("../lib/environments/chrome-worker.js"),
     "frame-script": require("../lib/environments/frame-script.js"),
-    jsm: require("../lib/environments/jsm.js"),
+    sysmjs: require("../lib/environments/sysmjs.js"),
     privileged: require("../lib/environments/privileged.js"),
     "process-script": require("../lib/environments/process-script.js"),
     "remote-page": require("../lib/environments/remote-page.js"),