diff --git a/.changeset/shiny-kiwis-smash.md b/.changeset/shiny-kiwis-smash.md
new file mode 100644
index 00000000..c47e81f4
--- /dev/null
+++ b/.changeset/shiny-kiwis-smash.md
@@ -0,0 +1,5 @@
+---
+"abitype": patch
+---
+
+Updated `TypedDataDomain` `chainId` to support `uint256` values via `bigint`.
diff --git a/packages/abitype/src/abi.ts b/packages/abitype/src/abi.ts
index 90247c54..1eaa84ca 100644
--- a/packages/abitype/src/abi.ts
+++ b/packages/abitype/src/abi.ts
@@ -218,7 +218,7 @@ export type Abi = readonly (
 // Typed Data Types
 
 export type TypedDataDomain = {
-  chainId?: number | undefined
+  chainId?: number | bigint | undefined
   name?: string | undefined
   salt?: ResolvedRegister['bytesType']['outputs'] | undefined
   verifyingContract?: Address | undefined
diff --git a/packages/abitype/src/zod.ts b/packages/abitype/src/zod.ts
index 76a5d024..87ef4a18 100644
--- a/packages/abitype/src/zod.ts
+++ b/packages/abitype/src/zod.ts
@@ -299,7 +299,7 @@ export const Abi = z
 // Typed Data Types
 
 export const TypedDataDomain = z.object({
-  chainId: z.number().optional(),
+  chainId: z.union([z.number(), z.bigint()]).optional(),
   name: Identifier.optional(),
   salt: z.string().optional(),
   verifyingContract: Address.optional(),