diff --git a/.changeset/okx-cosmos-v3.md b/.changeset/okx-cosmos-v3.md
new file mode 100644
index 0000000..2fd53b3
--- /dev/null
+++ b/.changeset/okx-cosmos-v3.md
@@ -0,0 +1,5 @@
+---
+"@swapkit/wallet-extensions": patch
+---
+
+OKX: pass the Keplr-compatible offline signer into `getCosmosToolbox` so the toolbox can synthesize `signAndBroadcastTransaction`, unblocking the V3 SwapKit swap flow for OKX Cosmos.
diff --git a/packages/wallet-extensions/src/okx/helpers.ts b/packages/wallet-extensions/src/okx/helpers.ts
index a9406c6..c5880ce 100644
--- a/packages/wallet-extensions/src/okx/helpers.ts
+++ b/packages/wallet-extensions/src/okx/helpers.ts
@@ -134,7 +134,7 @@ export async function getWalletMethods(chain: Chain) {
 
         const { getCosmosToolbox } = await import("@swapkit/toolboxes/cosmos");
         const [{ address }] = accounts;
-        const toolbox = getCosmosToolbox(Chain.Cosmos);
+        const toolbox = await getCosmosToolbox(Chain.Cosmos, { signer: offlineSigner });
 
         return { ...toolbox, address, transfer: cosmosTransfer(address) };
       })