diff --git a/types/eslint/eslint-tests.ts b/types/eslint/eslint-tests.ts
index 460703dd59..44642aef3e 100644
--- a/types/eslint/eslint-tests.ts
+++ b/types/eslint/eslint-tests.ts
@@ -1007,4 +1007,32 @@ ruleTester.run('simple-valid-test', rule, {
     }
 });
 
+(): Linter.FlatConfig => ({ files: ["abc"] });
+(): Linter.FlatConfig => ({ files: [(path) => false] });
+(): Linter.FlatConfig => ({ files: [["abc"]]});
+(): Linter.FlatConfig => ({ files: [[(path) => false]] });
+(): Linter.FlatConfig => ({ files: [["abc", (path) => false]] });
+(): Linter.FlatConfig => ({ files: ["abc", (path) => false, ["abc"], [(path) => false], ["abc", (path) => false]] });
+
+// @ts-expect-error // Second level of nesting is not allowed
+(): Linter.FlatConfig => ({ files: ["abc", (path) => false, ["abc"], [(path) => false], ["abc", (path) => false], [["abc"], [(path) => false]]] });
+
+(): Linter.FlatConfig => ({ ignores: ["abc"] });
+(): Linter.FlatConfig => ({ ignores: [(path) => false] });
+(): Linter.FlatConfig => ({ ignores: ["abc", (path) => false] });
+
+// @ts-expect-error // No nesting
+(): Linter.FlatConfig => ({ ignores: ["abc", (path) => false, ["abc"], [(path) => false], ["abc", (path) => false]] });
+
+// @ts-expect-error // Must be an array
+(): Linter.FlatConfig => ({ files: "abc" });
+
+// @ts-expect-error // Must be an array
+(): Linter.FlatConfig => ({ ignores: "abc" });
+
+// The following _should_ be an error, but we can't enforce on consumers
+// as it requires exactOptionalPropertyTypes: true
+// (): Linter.FlatConfig => ({ files: undefined });
+// (): Linter.FlatConfig => ({ ignores: undefined });
+
 //#endregion
diff --git a/types/eslint/index.d.ts b/types/eslint/index.d.ts
index 504e5a8730..255cbcca0f 100644
--- a/types/eslint/index.d.ts
+++ b/types/eslint/index.d.ts
@@ -933,19 +933,22 @@ export namespace Linter {
         preprocess?(text: string, filename: string): T[];
         postprocess?(messages: LintMessage[][], filename: string): LintMessage[];
     }
+
+    type FlatConfigFileSpec = string | ((filePath: string) => boolean);
+
     interface FlatConfig {
       /**
        * An array of glob patterns indicating the files that the configuration
        * object should apply to. If not specified, the configuration object applies
        * to all files
        */
-      files?: string | string[];
+      files?: Array<FlatConfigFileSpec | FlatConfigFileSpec[]>;
       /**
        * An array of glob patterns indicating the files that the configuration
        * object should not apply to. If not specified, the configuration object
        * applies to all files matched by files
        */
-      ignores?: string | string[];
+      ignores?: FlatConfigFileSpec[];
       /**
        * An object containing settings related to how JavaScript is configured for
        * linting.