diff --git a/packages/eslint-plugin/src/rules/no-shadow.ts b/packages/eslint-plugin/src/rules/no-shadow.ts
index e6ceb4f3b918..fa79c362ec50 100644
--- a/packages/eslint-plugin/src/rules/no-shadow.ts
+++ b/packages/eslint-plugin/src/rules/no-shadow.ts
@@ -3,7 +3,7 @@ import type { TSESLint, TSESTree } from '@typescript-eslint/utils';
 import { DefinitionType, ScopeType } from '@typescript-eslint/scope-manager';
 import { AST_NODE_TYPES, ASTUtils } from '@typescript-eslint/utils';
 
-import { createRule } from '../util';
+import { createRule, isDefinitionFile } from '../util';
 import { isTypeImport } from '../util/isTypeImport';
 
 export type MessageIds = 'noShadow' | 'noShadowGlobal';
@@ -566,6 +566,25 @@ export default createRule<Options, MessageIds>({
       };
     }
 
+    /**
+     * Checks if the initialization of a variable has the declare modifier in a
+     * definition file.
+     */
+    function isDeclareInDTSFile(variable: TSESLint.Scope.Variable): boolean {
+      const fileName = context.filename;
+      if (!isDefinitionFile(fileName)) {
+        return false;
+      }
+      return variable.defs.some(def => {
+        return (
+          (def.type === DefinitionType.Variable && def.parent.declare) ||
+          (def.type === DefinitionType.ClassName && def.node.declare) ||
+          (def.type === DefinitionType.TSEnumName && def.node.declare) ||
+          (def.type === DefinitionType.TSModuleName && def.node.declare)
+        );
+      });
+    }
+
     /**
      * Checks the current context for shadowed variables.
      * @param scope Fixme
@@ -604,6 +623,11 @@ export default createRule<Options, MessageIds>({
           continue;
         }
 
+        // ignore variables with the declare keyword in .d.ts files
+        if (isDeclareInDTSFile(variable)) {
+          continue;
+        }
+
         // Gets shadowed variable.
         const shadowed = scope.upper
           ? ASTUtils.findVariable(scope.upper, variable.name)
diff --git a/packages/eslint-plugin/tests/rules/no-shadow/no-shadow.test.ts b/packages/eslint-plugin/tests/rules/no-shadow/no-shadow.test.ts
index 22e04824b877..1378a1785ae2 100644
--- a/packages/eslint-plugin/tests/rules/no-shadow/no-shadow.test.ts
+++ b/packages/eslint-plugin/tests/rules/no-shadow/no-shadow.test.ts
@@ -847,6 +847,48 @@ function foo<T extends (...args: any[]) => any>(fn: T, args: any[]) {}
         },
       ],
     },
+    {
+      code: `
+declare const has = (environment: 'dev' | 'prod' | 'test') => boolean;
+      `,
+      errors: [
+        {
+          data: {
+            name: 'has',
+          },
+          messageId: 'noShadowGlobal',
+        },
+      ],
+      languageOptions: {
+        globals: {
+          has: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
+    {
+      code: `
+declare const has: (environment: 'dev' | 'prod' | 'test') => boolean;
+const fn = (has: string) => {};
+      `,
+      errors: [
+        {
+          data: {
+            name: 'has',
+            shadowedColumn: 15,
+            shadowedLine: 2,
+          },
+          messageId: 'noShadow',
+        },
+      ],
+      filename: 'foo.d.ts',
+      languageOptions: {
+        globals: {
+          has: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
   ],
   valid: [
     'function foo<T = (arg: any) => any>(arg: T) {}',
@@ -1455,5 +1497,134 @@ declare module 'bar' {
 }
       `,
     },
+    {
+      code: `
+declare const foo1: boolean;
+      `,
+      filename: 'baz.d.ts',
+      languageOptions: {
+        globals: {
+          foo1: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
+    {
+      code: `
+declare let foo2: boolean;
+      `,
+      filename: 'baz.d.ts',
+      languageOptions: {
+        globals: {
+          foo2: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
+    {
+      code: `
+declare var foo3: boolean;
+      `,
+      filename: 'baz.d.ts',
+      languageOptions: {
+        globals: {
+          foo3: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
+    {
+      code: `
+function foo4(name: string): void;
+      `,
+      filename: 'baz.d.ts',
+      languageOptions: {
+        globals: {
+          foo4: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
+    {
+      code: `
+declare class Foopy1 {
+  name: string;
+}
+      `,
+      filename: 'baz.d.ts',
+      languageOptions: {
+        globals: {
+          Foopy1: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
+    {
+      code: `
+declare interface Foopy2 {
+  name: string;
+}
+      `,
+      filename: 'baz.d.ts',
+      languageOptions: {
+        globals: {
+          Foopy2: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
+    {
+      code: `
+declare type Foopy3 = {
+  x: number;
+};
+      `,
+      filename: 'baz.d.ts',
+      languageOptions: {
+        globals: {
+          Foopy3: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
+    {
+      code: `
+declare enum Foopy4 {
+  x,
+}
+      `,
+      filename: 'baz.d.ts',
+      languageOptions: {
+        globals: {
+          Foopy4: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
+    {
+      code: `
+declare namespace Foopy5 {}
+      `,
+      filename: 'baz.d.ts',
+      languageOptions: {
+        globals: {
+          Foopy5: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
+    {
+      code: `
+declare;
+foo5: boolean;
+      `,
+      filename: 'baz.d.ts',
+      languageOptions: {
+        globals: {
+          foo5: false,
+        },
+      },
+      options: [{ builtinGlobals: true }],
+    },
   ],
 });