diff --git a/beacon_node/beacon_chain/src/payload_envelope_verification/import.rs b/beacon_node/beacon_chain/src/payload_envelope_verification/import.rs
index ed121ccb94..6efabcdfa8 100644
--- a/beacon_node/beacon_chain/src/payload_envelope_verification/import.rs
+++ b/beacon_node/beacon_chain/src/payload_envelope_verification/import.rs
@@ -167,6 +167,16 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             .map_err(BeaconChainError::TokioJoin)?
             .ok_or(BeaconChainError::RuntimeShutdown)??;
 
+        // TODO(gloas): optimistic sync is not supported for Gloas, maybe we could re-add it
+        if payload_verification_outcome
+            .payload_verification_status
+            .is_optimistic()
+        {
+            return Err(EnvelopeError::OptimisticSyncNotSupported {
+                block_root: import_data.block_root,
+            });
+        }
+
         Ok(ExecutedEnvelope::new(
             signed_envelope,
             import_data,
diff --git a/beacon_node/beacon_chain/src/payload_envelope_verification/mod.rs b/beacon_node/beacon_chain/src/payload_envelope_verification/mod.rs
index c707d62dc7..225d5a9892 100644
--- a/beacon_node/beacon_chain/src/payload_envelope_verification/mod.rs
+++ b/beacon_node/beacon_chain/src/payload_envelope_verification/mod.rs
@@ -182,6 +182,8 @@ pub enum EnvelopeError {
         payload_slot: Slot,
         latest_finalized_slot: Slot,
     },
+    /// Optimistic sync is not supported for Gloas payload envelopes.
+    OptimisticSyncNotSupported { block_root: Hash256 },
     /// Some Beacon Chain Error
     BeaconChainError(Arc<BeaconChainError>),
     /// Some Beacon State error