diff --git a/.editorconfig b/.editorconfig
index 12562f79..0ba33458 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -3,6 +3,6 @@ charset = utf-8
 end_of_line = lf
 insert_final_newline = true
 
-[*.{js, json, sh, yml}]
+[*.{js, mjs, json, sh, yml}]
 indent_style = space
 indent_size = 2
diff --git a/eslint.config.mjs b/eslint.config.mjs
new file mode 100644
index 00000000..afe200f2
--- /dev/null
+++ b/eslint.config.mjs
@@ -0,0 +1,54 @@
+import { defineConfig } from "eslint/config";
+import globals from "globals";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import js from "@eslint/js";
+import { FlatCompat } from "@eslint/eslintrc";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const compat = new FlatCompat({
+  baseDirectory: __dirname,
+  recommendedConfig: js.configs.recommended,
+  allConfig: js.configs.all
+});
+
+export default defineConfig([{
+  extends: compat.extends("plugin:compat/recommended"),
+
+  languageOptions: {
+    globals: {
+      ...globals.browser,
+      ...globals.node,
+    },
+
+    ecmaVersion: 2018,
+    sourceType: "commonjs",
+  },
+
+  rules: {
+    curly: "error",
+
+    quotes: ["error", "single", {
+      avoidEscape: true,
+    }],
+
+    "no-unused-vars": ["error", {
+      args: "none",
+    }],
+
+    "no-implicit-globals": "error",
+    "block-spacing": "error",
+    "func-call-spacing": ["error", "never"],
+    "key-spacing": "error",
+    "no-tabs": "error",
+    "no-trailing-spaces": "error",
+    "no-whitespace-before-property": "error",
+    semi: ["error", "always"],
+    "space-before-blocks": "error",
+    "no-eval": "error",
+    "no-var": "error",
+    "no-debugger": "error",
+    "no-console": "error",
+  },
+}]);
diff --git a/package.json b/package.json
index 2188cf2e..a7938fe7 100644
--- a/package.json
+++ b/package.json
@@ -34,9 +34,12 @@
     "package.json"
   ],
   "devDependencies": {
-    "eslint": "^8.36.0",
-    "eslint-plugin-compat": "^4.0.0",
+    "@eslint/eslintrc": "^3.3.1",
+    "@eslint/js": "^9.24.0",
+    "eslint": "^9.24.0",
+    "eslint-plugin-compat": "^6.0.2",
     "glob": "^10.2.3",
+    "globals": "^16.0.0",
     "grunt": "^1.0.4",
     "grunt-cli": "^1.3.2",
     "grunt-contrib-compress": "^2.0.0",
diff --git a/spec/core/EnvSpec.js b/spec/core/EnvSpec.js
index f9f74ef3..a3753f77 100644
--- a/spec/core/EnvSpec.js
+++ b/spec/core/EnvSpec.js
@@ -205,7 +205,6 @@ describe('Env', function() {
 
     it('throws an error when given arguments', function() {
       expect(function() {
-        // eslint-disable-next-line no-unused-vars
         env.describe('done method', function(done) {});
       }).toThrowError('describe does not expect any arguments');
     });
diff --git a/spec/core/QueueRunnerSpec.js b/spec/core/QueueRunnerSpec.js
index 0e8b2690..847d5716 100644
--- a/spec/core/QueueRunnerSpec.js
+++ b/spec/core/QueueRunnerSpec.js
@@ -239,7 +239,6 @@ describe('QueueRunner', function() {
 
     it("sets a timeout if requested for asynchronous functions so they don't go on forever", function() {
       const timeout = 3,
-        // eslint-disable-next-line no-unused-vars
         beforeFn = { fn: function(done) {}, type: 'before', timeout: timeout },
         queueableFn = { fn: jasmine.createSpy('fn'), type: 'queueable' },
         onComplete = jasmine.createSpy('onComplete'),
@@ -287,7 +286,6 @@ describe('QueueRunner', function() {
     });
 
     it('by default does not set a timeout for asynchronous functions', function() {
-      // eslint-disable-next-line no-unused-vars
       const beforeFn = { fn: function(done) {} },
         queueableFn = { fn: jasmine.createSpy('fn') },
         onComplete = jasmine.createSpy('onComplete'),
@@ -310,7 +308,6 @@ describe('QueueRunner', function() {
 
     it('clears the timeout when an async function throws an exception, to prevent additional exception reporting', function() {
       const queueableFn = {
-          // eslint-disable-next-line no-unused-vars
           fn: function(done) {
             throw new Error('error!');
           }
@@ -409,7 +406,6 @@ describe('QueueRunner', function() {
 
     it('continues running functions when an exception is thrown in async code without timing out', function() {
       const queueableFn = {
-          // eslint-disable-next-line no-unused-vars
           fn: function(done) {
             throwAsync();
           },
@@ -461,7 +457,6 @@ describe('QueueRunner', function() {
 
     it('handles a global error event with a message but no error', function() {
       const queueableFn = {
-        // eslint-disable-next-line no-unused-vars
         fn: function(done) {
           const currentHandler = globalErrors.pushListener.calls.mostRecent()
             .args[0];
@@ -641,7 +636,6 @@ describe('QueueRunner', function() {
 
     it('issues an error if the function also takes a parameter', function() {
       const queueableFn = {
-          // eslint-disable-next-line no-unused-vars
           fn: function(done) {
             return new StubPromise();
           }
@@ -666,7 +660,6 @@ describe('QueueRunner', function() {
     });
 
     it('issues a more specific error if the function is `async`', function() {
-      // eslint-disable-next-line no-unused-vars
       async function fn(done) {}
       const onException = jasmine.createSpy('onException'),
         queueRunner = new jasmineUnderTest.QueueRunner({
@@ -720,7 +713,6 @@ describe('QueueRunner', function() {
 
   it('continues running the functions even after an exception is thrown in an async spec', function() {
     const queueableFn = {
-        // eslint-disable-next-line no-unused-vars
         fn: function(done) {
           throw new Error('error');
         }
diff --git a/spec/core/SpySpec.js b/spec/core/SpySpec.js
index 2390b4fc..323bd5ca 100644
--- a/spec/core/SpySpec.js
+++ b/spec/core/SpySpec.js
@@ -97,17 +97,11 @@ describe('Spies', function() {
     it('preserves arity of original function', function() {
       const functions = [
         function nullary() {},
-        // eslint-disable-next-line no-unused-vars
         function unary(arg) {},
-        // eslint-disable-next-line no-unused-vars
         function binary(arg1, arg2) {},
-        // eslint-disable-next-line no-unused-vars
         function ternary(arg1, arg2, arg3) {},
-        // eslint-disable-next-line no-unused-vars
         function quaternary(arg1, arg2, arg3, arg4) {},
-        // eslint-disable-next-line no-unused-vars
         function quinary(arg1, arg2, arg3, arg4, arg5) {},
-        // eslint-disable-next-line no-unused-vars
         function senary(arg1, arg2, arg3, arg4, arg5, arg6) {}
       ];
 
diff --git a/spec/core/integration/EnvSpec.js b/spec/core/integration/EnvSpec.js
index e50647e5..f5d2940f 100644
--- a/spec/core/integration/EnvSpec.js
+++ b/spec/core/integration/EnvSpec.js
@@ -1071,7 +1071,6 @@ describe('Env integration', function() {
       env.describe('my suite', function() {
         env.it('my spec', function() {});
 
-        // eslint-disable-next-line no-unused-vars
         env.afterAll(function(afterAllDone) {
           throw error;
         });
@@ -1569,7 +1568,6 @@ describe('Env integration', function() {
       env.addReporter(reporter);
       jasmineUnderTest.DEFAULT_TIMEOUT_INTERVAL = 8414;
 
-      // eslint-disable-next-line no-unused-vars
       env.it("async spec that doesn't call done", function(underTestCallback) {
         env.expect(true).toBeTruthy();
         jasmine.clock().tick(8416);
@@ -1642,13 +1640,13 @@ describe('Env integration', function() {
           realSetTimeout(function() {
             try {
               jasmine.clock().tick(10);
+              // eslint-disable-next-line no-unused-vars
             } catch (e) {
               // don't worry if the clock is already uninstalled
             }
           }, 100);
         });
         env.describe('beforeAll', function() {
-          // eslint-disable-next-line no-unused-vars
           env.beforeAll(function(innerDone) {
             realSetTimeout(function() {
               jasmine.clock().tick(5001);
@@ -1664,7 +1662,6 @@ describe('Env integration', function() {
         });
 
         env.describe('afterAll', function() {
-          // eslint-disable-next-line no-unused-vars
           env.afterAll(function(innerDone) {
             realSetTimeout(function() {
               jasmine.clock().tick(2001);
@@ -1680,7 +1677,6 @@ describe('Env integration', function() {
         });
 
         env.describe('beforeEach', function() {
-          // eslint-disable-next-line no-unused-vars
           env.beforeEach(function(innerDone) {
             realSetTimeout(function() {
               jasmine.clock().tick(1001);
@@ -1696,7 +1692,6 @@ describe('Env integration', function() {
         });
 
         env.describe('afterEach', function() {
-          // eslint-disable-next-line no-unused-vars
           env.afterEach(function(innerDone) {
             realSetTimeout(function() {
               jasmine.clock().tick(4001);
@@ -1713,7 +1708,6 @@ describe('Env integration', function() {
 
         env.it(
           'it times out',
-          // eslint-disable-next-line no-unused-vars
           function(innerDone) {
             realSetTimeout(function() {
               jasmine.clock().tick(6001);
@@ -2699,7 +2693,6 @@ describe('Env integration', function() {
     env.addReporter(reporter);
 
     env.describe('async suite', function() {
-      // eslint-disable-next-line no-unused-vars
       env.afterAll(function(innerDone) {
         setTimeout(function() {
           throw new Error('suite');
@@ -2712,7 +2705,6 @@ describe('Env integration', function() {
     env.describe('suite', function() {
       env.it(
         'async spec',
-        // eslint-disable-next-line no-unused-vars
         function(innerDone) {
           setTimeout(function() {
             throw new Error('spec');
@@ -4362,6 +4354,7 @@ describe('Env integration', function() {
       env.it('a spec', function() {
         try {
           env.throwUnless(1).toEqual(1);
+          // eslint-disable-next-line no-unused-vars
         } catch (e) {
           threw = true;
         }
@@ -4375,6 +4368,7 @@ describe('Env integration', function() {
       env.it('a spec', function() {
         try {
           env.throwUnless(1).toEqual(2);
+          // eslint-disable-next-line no-unused-vars
         } catch (e) {}
       });
 
@@ -4418,6 +4412,7 @@ describe('Env integration', function() {
       env.it('a spec', async function() {
         try {
           await env.throwUnlessAsync(Promise.resolve()).toBeResolved();
+          // eslint-disable-next-line no-unused-vars
         } catch (e) {
           threw = true;
         }
@@ -4431,6 +4426,7 @@ describe('Env integration', function() {
       env.it('a spec', async function() {
         try {
           await env.throwUnlessAsync(Promise.resolve()).toBeRejected();
+          // eslint-disable-next-line no-unused-vars
         } catch (e) {}
       });
 
diff --git a/spec/core/integration/SpecRunningSpec.js b/spec/core/integration/SpecRunningSpec.js
index 32439a3a..a680949a 100644
--- a/spec/core/integration/SpecRunningSpec.js
+++ b/spec/core/integration/SpecRunningSpec.js
@@ -866,7 +866,6 @@ describe('spec running', function() {
       const actions = [];
 
       env.describe('Something', function() {
-        // eslint-disable-next-line no-unused-vars
         env.beforeEach(function(innerDone) {
           actions.push('beforeEach');
         }, 1);
diff --git a/spec/core/matchers/matchersUtilSpec.js b/spec/core/matchers/matchersUtilSpec.js
index 798fbe94..27460933 100644
--- a/spec/core/matchers/matchersUtilSpec.js
+++ b/spec/core/matchers/matchersUtilSpec.js
@@ -830,9 +830,7 @@ describe('matchersUtil', function() {
             const matchersUtil = new jasmineUnderTest.MatchersUtil();
             const a1 = new TypedArrayCtor(2);
             const a2 = new TypedArrayCtor(2);
-            // eslint-disable-next-line compat/compat
             a1[0] = a2[0] = BigInt(0);
-            // eslint-disable-next-line compat/compat
             a1[1] = a2[1] = BigInt(1);
             expect(matchersUtil.equals(a1, a2)).toBe(true);
           }
@@ -843,7 +841,6 @@ describe('matchersUtil', function() {
           const matchersUtil = new jasmineUnderTest.MatchersUtil();
           const a1 = new TypedArrayCtor(2);
           const a2 = new TypedArrayCtor(1);
-          // eslint-disable-next-line compat/compat
           a1[0] = a1[1] = a2[0] = BigInt(0);
           expect(matchersUtil.equals(a1, a2)).toBe(false);
         });
@@ -855,9 +852,7 @@ describe('matchersUtil', function() {
             const matchersUtil = new jasmineUnderTest.MatchersUtil();
             const a1 = new TypedArrayCtor(2);
             const a2 = new TypedArrayCtor(2);
-            // eslint-disable-next-line compat/compat
             a1[0] = a1[1] = a2[0] = BigInt(0);
-            // eslint-disable-next-line compat/compat
             a2[1] = BigInt(1);
             expect(matchersUtil.equals(a1, a2)).toBe(false);
           }
diff --git a/spec/core/matchers/toEqualSpec.js b/spec/core/matchers/toEqualSpec.js
index 868bd2f5..55b5d9d9 100644
--- a/spec/core/matchers/toEqualSpec.js
+++ b/spec/core/matchers/toEqualSpec.js
@@ -1,4 +1,3 @@
-/* eslint-disable compat/compat */
 describe('toEqual', function() {
   'use strict';
 
diff --git a/spec/core/matchers/toHaveNoOtherSpyInteractionsSpec.js b/spec/core/matchers/toHaveNoOtherSpyInteractionsSpec.js
index 8f41b34b..ddb669c4 100644
--- a/spec/core/matchers/toHaveNoOtherSpyInteractionsSpec.js
+++ b/spec/core/matchers/toHaveNoOtherSpyInteractionsSpec.js
@@ -85,7 +85,7 @@ describe('toHaveNoOtherSpyInteractions', function() {
     );
   });
 
-  it(`throws an error if a non-object is passed`, function() {
+  it('throws an error if a non-object is passed', function() {
     let matcher = jasmineUnderTest.matchers.toHaveNoOtherSpyInteractions();
 
     expect(function() {
diff --git a/spec/core/matchers/toHaveSpyInteractionsSpec.js b/spec/core/matchers/toHaveSpyInteractionsSpec.js
index 3d0e577c..d5b71f83 100755
--- a/spec/core/matchers/toHaveSpyInteractionsSpec.js
+++ b/spec/core/matchers/toHaveSpyInteractionsSpec.js
@@ -70,7 +70,7 @@ describe('toHaveSpyInteractions', function() {
     );
   });
 
-  it(`throws an error if a non-object is passed`, function() {
+  it('throws an error if a non-object is passed', function() {
     let matcher = jasmineUnderTest.matchers.toHaveSpyInteractions();
 
     expect(function() {
diff --git a/spec/support/ci.js b/spec/support/ci.js
index 6757446d..5a9ccb2e 100644
--- a/spec/support/ci.js
+++ b/spec/support/ci.js
@@ -8,6 +8,7 @@ config.clearReporters = true;
 config.jasmineCore = jasmineCore;
 
 jasmineBrowser.runSpecs(config).catch(function(error) {
+  // eslint-disable-next-line no-console
   console.error(error);
   process.exit(1);
 });
diff --git a/src/core/Deprecator.js b/src/core/Deprecator.js
index 65fc6e38..59726da8 100644
--- a/src/core/Deprecator.js
+++ b/src/core/Deprecator.js
@@ -36,6 +36,7 @@ getJasmineRequireObj().Deprecator = function(j$) {
 
   Deprecator.prototype.log_ = function(runnable, deprecation, options) {
     if (j$.isError_(deprecation)) {
+      // eslint-disable-next-line no-console
       console.error(deprecation);
       return;
     }
@@ -58,6 +59,7 @@ getJasmineRequireObj().Deprecator = function(j$) {
       context += '\n' + verboseNote;
     }
 
+    // eslint-disable-next-line no-console
     console.error('DEPRECATION: ' + deprecation + context);
   };
 
diff --git a/src/core/Env.js b/src/core/Env.js
index d546dc4e..a15a0a18 100644
--- a/src/core/Env.js
+++ b/src/core/Env.js
@@ -385,7 +385,9 @@ getJasmineRequireObj().Env = function(j$) {
 
       // If we get here, all results have been reported and there's nothing we
       // can do except log the result and hope the user sees it.
+      // eslint-disable-next-line no-console
       console.error('Jasmine received a result after the suite finished:');
+      // eslint-disable-next-line no-console
       console.error(expectationResult);
     }
 
diff --git a/src/core/PrettyPrinter.js b/src/core/PrettyPrinter.js
index bc6b2224..9a098f21 100644
--- a/src/core/PrettyPrinter.js
+++ b/src/core/PrettyPrinter.js
@@ -58,6 +58,7 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
         ) {
           try {
             this.emitScalar(value.toString());
+            // eslint-disable-next-line no-unused-vars
           } catch (e) {
             this.emitScalar('has-invalid-toString-method');
           }
@@ -304,6 +305,7 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
         value.toString !== Object.prototype.toString &&
         value.toString() !== Object.prototype.toString.call(value)
       );
+      // eslint-disable-next-line no-unused-vars
     } catch (e) {
       // The custom toString() threw.
       return true;
diff --git a/src/core/QueueRunner.js b/src/core/QueueRunner.js
index 034233e6..007c5e8f 100644
--- a/src/core/QueueRunner.js
+++ b/src/core/QueueRunner.js
@@ -22,6 +22,7 @@ getJasmineRequireObj().QueueRunner = function(j$) {
   }
 
   function fallbackOnMultipleDone() {
+    // eslint-disable-next-line no-console
     console.error(
       new Error(
         "An asynchronous function called its 'done' " +
@@ -135,6 +136,7 @@ getJasmineRequireObj().QueueRunner = function(j$) {
           // Any error we catch here is probably due to a bug in Jasmine,
           // and it's not likely to end up anywhere useful if we let it
           // propagate. Log it so it can at least show up when debugging.
+          // eslint-disable-next-line no-console
           console.error(error);
         }
       }
diff --git a/src/core/SpyRegistry.js b/src/core/SpyRegistry.js
index ba129924..fece1b44 100644
--- a/src/core/SpyRegistry.js
+++ b/src/core/SpyRegistry.js
@@ -252,6 +252,7 @@ getJasmineRequireObj().SpyRegistry = function(j$) {
     let value;
     try {
       value = obj[prop];
+      // eslint-disable-next-line no-unused-vars
     } catch (e) {
       return false;
     }
diff --git a/src/core/matchers/toBeInstanceOf.js b/src/core/matchers/toBeInstanceOf.js
index 5e0156ee..fba86e9c 100644
--- a/src/core/matchers/toBeInstanceOf.js
+++ b/src/core/matchers/toBeInstanceOf.js
@@ -31,6 +31,7 @@ getJasmineRequireObj().toBeInstanceOf = function(j$) {
         try {
           expectedMatcher = new j$.Any(expected);
           pass = expectedMatcher.asymmetricMatch(actual);
+          // eslint-disable-next-line no-unused-vars
         } catch (error) {
           throw new Error(
             usageError('Expected value is not a constructor function')
diff --git a/src/html/HtmlReporter.js b/src/html/HtmlReporter.js
index 43053fbd..63c5813e 100644
--- a/src/html/HtmlReporter.js
+++ b/src/html/HtmlReporter.js
@@ -122,8 +122,10 @@ jasmineRequire.HtmlReporter = function(j$) {
       if (noExpectations(result)) {
         const noSpecMsg = "Spec '" + result.fullName + "' has no expectations.";
         if (result.status === 'failed') {
+          // eslint-disable-next-line no-console
           console.error(noSpecMsg);
         } else {
+          // eslint-disable-next-line no-console
           console.warn(noSpecMsg);
         }
       }