diff --git a/.changeset/kind-lands-know.md b/.changeset/kind-lands-know.md
new file mode 100644
index 0000000000..7aa44eefb0
--- /dev/null
+++ b/.changeset/kind-lands-know.md
@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Added GIWA Sepolia chain.
diff --git a/src/chains/definitions/giwaSepolia.ts b/src/chains/definitions/giwaSepolia.ts
new file mode 100644
index 0000000000..cfe92a8682
--- /dev/null
+++ b/src/chains/definitions/giwaSepolia.ts
@@ -0,0 +1,49 @@
+import { chainConfig } from '../../op-stack/chainConfig.js'
+import { defineChain } from '../../utils/chain/defineChain.js'
+
+const sourceId = 11_155_111 // sepolia
+
+export const giwaSepolia = /*#__PURE__*/ defineChain({
+  ...chainConfig,
+  id: 91342,
+  network: 'giwa-sepolia',
+  name: 'GIWA Sepolia',
+  nativeCurrency: { name: 'Sepolia Ether', symbol: 'ETH', decimals: 18 },
+  blockTime: 1_000,
+  rpcUrls: {
+    default: {
+      http: ['https://sepolia-rpc.giwa.io'],
+    },
+  },
+  blockExplorers: {
+    default: {
+      name: 'Blockscout',
+      url: 'https://sepolia-explorer.giwa.io',
+      apiUrl: 'https://sepolia-explorer.giwa.io/api',
+    },
+  },
+  contracts: {
+    ...chainConfig.contracts,
+    multicall3: {
+      address: '0xcA11bde05977b3631167028862bE2a173976CA11',
+      blockCreated: 0,
+    },
+    disputeGameFactory: {
+      [sourceId]: {
+        address: '0x37347caB2afaa49B776372279143D71ad1f354F6',
+      },
+    },
+    portal: {
+      [sourceId]: {
+        address: '0x956962C34687A954e611A83619ABaA37Ce6bC78A',
+      },
+    },
+    l1StandardBridge: {
+      [sourceId]: {
+        address: '0x77b2ffc0F57598cAe1DB76cb398059cF5d10A7E7',
+      },
+    },
+  },
+  testnet: true,
+  sourceId,
+})
diff --git a/src/chains/index.ts b/src/chains/index.ts
index 4008609287..169d48e5b7 100644
--- a/src/chains/index.ts
+++ b/src/chains/index.ts
@@ -220,6 +220,7 @@ export { fusionTestnet } from './definitions/fusionTestnet.js'
 export { garnet } from './definitions/garnet.js'
 export { geist } from './definitions/geist.js'
 export { genesys } from './definitions/genesys.js'
+export { giwaSepolia } from './definitions/giwaSepolia.js'
 export { glideL1Protocol } from './definitions/glideL1Protocol.js'
 export { glideL2Protocol } from './definitions/glideL2Protocol.js'
 export { gnosis } from './definitions/gnosis.js'