diff --git a/.changeset/onramp-success-guard.md b/.changeset/onramp-success-guard.md
new file mode 100644
index 00000000000..51fd8da313c
--- /dev/null
+++ b/.changeset/onramp-success-guard.md
@@ -0,0 +1,5 @@
+---
+"thirdweb": patch
+---
+
+Fixed Universal Bridge onramp checkout incorrectly reporting success when the onramp did not complete.
diff --git a/packages/thirdweb/src/react/core/hooks/useStepExecutor.ts b/packages/thirdweb/src/react/core/hooks/useStepExecutor.ts
index e0a8f024200..1f96be33dab 100644
--- a/packages/thirdweb/src/react/core/hooks/useStepExecutor.ts
+++ b/packages/thirdweb/src/react/core/hooks/useStepExecutor.ts
@@ -466,6 +466,7 @@ export function useStepExecutor(
           return { completed: true };
         } else if (status === "FAILED") {
           setOnrampStatus("failed");
+          throw new Error("Payment failed");
         }
 
         return { completed: false };
@@ -517,12 +518,25 @@ export function useStepExecutor(
       }
 
       // Execute onramp first if configured and not already completed
+      let onrampCompleted =
+        preparedQuote.type !== "onramp" || onrampStatus === "completed";
       if (preparedQuote.type === "onramp" && onrampStatus === "pending") {
         await executeOnramp(
           preparedQuote,
           completedStatusResults,
           abortController.signal,
         );
+        onrampCompleted = true;
+      }
+
+      // An onramp must complete before any follow-up transactions run or
+      // success is reported.
+      if (!onrampCompleted) {
+        throw new ApiError({
+          code: "INTERNAL_SERVER_ERROR",
+          message: "Onramp did not complete",
+          statusCode: 500,
+        });
       }
 
       if (flatTxs.length > 0) {