diff --git a/.changeset/keyed-nonce-rpc.md b/.changeset/keyed-nonce-rpc.md
new file mode 100644
index 000000000..ca96d6cfa
--- /dev/null
+++ b/.changeset/keyed-nonce-rpc.md
@@ -0,0 +1,12 @@
+---
+"ox": patch
+---
+
+Added optional `nonceKeys` to `eth_getTransactionCount` requests.
+
+```ts
+const nonce = await provider.request({
+  method: 'eth_getTransactionCount',
+  params: [address, 'pending', ['0x1', '0x2']],
+})
+```
diff --git a/src/core/_test/RpcSchema.test-d.ts b/src/core/_test/RpcSchema.test-d.ts
index 29b1694ac..f0e3ebbe5 100644
--- a/src/core/_test/RpcSchema.test-d.ts
+++ b/src/core/_test/RpcSchema.test-d.ts
@@ -1,5 +1,5 @@
 import type { RpcSchema } from 'ox'
-import { expectTypeOf, test } from 'vitest'
+import { describe, expectTypeOf, test } from 'vitest'
 
 test('ToViem: converts ox schema to viem schema', () => {
   type OxSchema =
@@ -161,3 +161,33 @@ test('frame simulation results expose payer and frame results', () => {
   expectTypeOf<Frame['stateGasUsed']>().toEqualTypeOf<`0x${string}`>()
   expectTypeOf<Frame['returnData']>().toEqualTypeOf<`0x${string}`>()
 })
+
+describe('Eth', () => {
+  test('eth_getTransactionCount', () => {
+    type Request = RpcSchema.ExtractRequest<
+      RpcSchema.Eth,
+      'eth_getTransactionCount'
+    >
+    type Params = Request['params']
+
+    expectTypeOf<['0x1234', 'latest']>().toMatchTypeOf<Params>()
+    expectTypeOf<
+      ['0x1234', 'pending', readonly ['0x0']]
+    >().toMatchTypeOf<Params>()
+    expectTypeOf<
+      ['0x1234', '0x10', readonly ['0x1', '0x2']]
+    >().toMatchTypeOf<Params>()
+    expectTypeOf<['0x1234', 'latest', undefined]>().toMatchTypeOf<Params>()
+    expectTypeOf<['0x1234', 'latest', '0x1']>().not.toMatchTypeOf<Params>()
+    expectTypeOf<
+      ['0x1234', 'latest', readonly [1n]]
+    >().not.toMatchTypeOf<Params>()
+    expectTypeOf<['0x1234', readonly ['0x1']]>().not.toMatchTypeOf<Params>()
+    expectTypeOf<
+      ['0x1234', 'latest', readonly ['0x1'], '0x2']
+    >().not.toMatchTypeOf<Params>()
+    expectTypeOf<
+      RpcSchema.ExtractReturnType<RpcSchema.Eth, 'eth_getTransactionCount'>
+    >().toEqualTypeOf<`0x${string}`>()
+  })
+})
diff --git a/src/core/internal/rpcSchemas/eth.ts b/src/core/internal/rpcSchemas/eth.ts
index 66b6eff1d..e9958dde8 100644
--- a/src/core/internal/rpcSchemas/eth.ts
+++ b/src/core/internal/rpcSchemas/eth.ts
@@ -557,7 +557,15 @@ export type Eth = RpcSchema.From<
       ReturnType: Transaction.Rpc | null
     }
   /**
-   * Returns the number of transactions sent from an address
+   * Returns the account nonce or the shared EIP-8250 sequence at the selected block.
+   *
+   * Omitted `nonceKeys` or `['0x0']` queries the account nonce. Nonzero keys query
+   * their shared sequence, with unused keys returning zero. `pending` uses pending state.
+   * Keys must be 1–16 canonical uint256 quantities in strictly increasing order;
+   * zero cannot be combined with other keys.
+   *
+   * Invalid keys return RPC error `-32602`. Differing sequences or EIP-8250 being
+   * inactive at the selected block for nonzero keys return `-32000`.
    *
    * @example
    * ```
@@ -575,6 +583,7 @@ export type Eth = RpcSchema.From<
             | Block.Tag
             | Block.Hash
             | Block.Identifier,
+          nonceKeys?: readonly Hex.Hex[] | undefined,
         ]
       }
       ReturnType: Hex.Hex