diff --git a/.changeset/eighty-humans-arrive.md b/.changeset/eighty-humans-arrive.md
new file mode 100644
index 0000000000..f11d549012
--- /dev/null
+++ b/.changeset/eighty-humans-arrive.md
@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Added Celo Sepolia chain.
diff --git a/src/chains/definitions/celoSepolia.ts b/src/chains/definitions/celoSepolia.ts
new file mode 100644
index 0000000000..7f93c636f2
--- /dev/null
+++ b/src/chains/definitions/celoSepolia.ts
@@ -0,0 +1,53 @@
+import { chainConfig } from '../../celo/chainConfig.js'
+import { defineChain } from '../../utils/chain/defineChain.js'
+
+const sourceId = 11_155_111 // sepolia
+// source https://storage.googleapis.com/cel2-rollup-files/celo-sepolia/deployment-l1.json
+export const celoSepolia = /*#__PURE__*/ defineChain({
+  ...chainConfig,
+  id: 11_142_220,
+  name: 'Celo Sepolia Testnet',
+  nativeCurrency: {
+    decimals: 18,
+    name: 'CELO',
+    symbol: 'S-CELO',
+  },
+  rpcUrls: {
+    default: {
+      http: ['https://forno.celo-sepolia.celo-testnet.org'],
+    },
+  },
+  blockExplorers: {
+    default: {
+      name: 'Celo Sepolia Explorer',
+      url: 'https://celo-sepolia.blockscout.com/',
+      apiUrl: 'https://celo-sepolia.blockscout.com/api',
+    },
+  },
+  contracts: {
+    ...chainConfig.contracts,
+    multicall3: {
+      address: '0xcA11bde05977b3631167028862bE2a173976CA11',
+      blockCreated: 1,
+    },
+    portal: {
+      [sourceId]: {
+        address: '0x44ae3d41a335a7d05eb533029917aad35662dcc2',
+        blockCreated: 8825790,
+      },
+    },
+    disputeGameFactory: {
+      [sourceId]: {
+        address: '0x57c45d82d1a995f1e135b8d7edc0a6bb5211cfaa',
+        blockCreated: 8825790,
+      },
+    },
+    l1StandardBridge: {
+      [sourceId]: {
+        address: '0xec18a3c30131a0db4246e785355fbc16e2eaf408',
+        blockCreated: 8825790,
+      },
+    },
+  },
+  testnet: true,
+})
diff --git a/src/chains/index.ts b/src/chains/index.ts
index 1173e96ae4..d8fa6a2df5 100644
--- a/src/chains/index.ts
+++ b/src/chains/index.ts
@@ -90,6 +90,7 @@ export { cannon } from './definitions/cannon.js'
 export { canto } from './definitions/canto.js'
 export { celo } from './definitions/celo.js'
 export { celoAlfajores } from './definitions/celoAlfajores.js'
+export { celoSepolia } from './definitions/celoSepolia.js'
 export { chang } from './definitions/chang.js'
 export { chiliz } from './definitions/chiliz.js'
 export { chips } from './definitions/chips.js'