diff --git a/.changeset/dull-lamps-repeat.md b/.changeset/dull-lamps-repeat.md
new file mode 100644
index 000000000..43f282369
--- /dev/null
+++ b/.changeset/dull-lamps-repeat.md
@@ -0,0 +1,5 @@
+---
+"@usedapp/core": patch
+---
+
+🌝 Add optimism sepolia to chain ids
diff --git a/packages/core/src/constants/chainId.ts b/packages/core/src/constants/chainId.ts
index 8f02f9838..78407bca7 100644
--- a/packages/core/src/constants/chainId.ts
+++ b/packages/core/src/constants/chainId.ts
@@ -68,6 +68,7 @@ import {
   MantleTestnet,
   KromaSepoliaTestnet,
   KromaMainnet,
+  OptimismSepolia,
 } from '../model'
 
 // rough alphabet order (put network from the same chain together)
@@ -121,6 +122,7 @@ export const DEFAULT_SUPPORTED_CHAINS = [
   ThunderCoreTestnet,
   OptimismGoerli,
   OptimismKovan,
+  OptimismSepolia,
   Optimism,
   Velas,
   VelasTestnet,
@@ -187,6 +189,7 @@ export enum ChainId {
   Andromeda = 1088,
   OptimismGoerli = 420,
   OptimismKovan = 69,
+  OptimismSepolia = 11155420,
   Optimism = 10,
   Arbitrum = 42161,
   ArbitrumRinkeby = 421611,
diff --git a/packages/core/src/hooks/useConfig.test.tsx b/packages/core/src/hooks/useConfig.test.tsx
index 990338728..48a44b930 100644
--- a/packages/core/src/hooks/useConfig.test.tsx
+++ b/packages/core/src/hooks/useConfig.test.tsx
@@ -26,7 +26,7 @@ describe('useConfig', () => {
     const { result, waitForCurrent } = await renderDAppHook(() => useConfig(), { config: setup.config })
     await waitForCurrent((val) => val !== undefined)
     expect(result.error).to.be.undefined
-    expect(result.current.networks?.length).to.eq(68)
+    expect(result.current.networks?.length).to.eq(69)
     expect(result.current.notifications?.checkInterval).to.eq(500)
     expect(result.current.notifications?.expirationPeriod).to.eq(5000)
   })