diff --git a/eth/executionclient/logs.go b/eth/executionclient/logs.go
index 37d421d891..cea62baa46 100644
--- a/eth/executionclient/logs.go
+++ b/eth/executionclient/logs.go
@@ -14,12 +14,20 @@ type BlockLogs struct {
 
 // PackLogs packs logs into []BlockLogs by their block number.
 func PackLogs(logs []ethtypes.Log) []BlockLogs {
-	// Sort the logs by block number.
+	// Sort into canonical on-chain order. The Index (logIndex) tiebreaker is what keeps logs
+	// emitted by the same transaction in order: sort.Slice is not stable, and a single tx can
+	// emit multiple order-dependent registry events (e.g. bulkRegisterValidator emits one
+	// ValidatorAdded per validator, each bumping the owner's nonce), which the handler must
+	// process in order. Without it, same-tx logs could be reordered and valid registrations
+	// silently rejected on a nonce mismatch.
 	sort.Slice(logs, func(i, j int) bool {
-		if logs[i].BlockNumber == logs[j].BlockNumber {
+		if logs[i].BlockNumber != logs[j].BlockNumber {
+			return logs[i].BlockNumber < logs[j].BlockNumber
+		}
+		if logs[i].TxIndex != logs[j].TxIndex {
 			return logs[i].TxIndex < logs[j].TxIndex
 		}
-		return logs[i].BlockNumber < logs[j].BlockNumber
+		return logs[i].Index < logs[j].Index
 	})
 
 	var all []BlockLogs
diff --git a/eth/executionclient/logs_test.go b/eth/executionclient/logs_test.go
index 9bbd3a7507..14594fcf24 100644
--- a/eth/executionclient/logs_test.go
+++ b/eth/executionclient/logs_test.go
@@ -83,3 +83,26 @@ func TestPackLogs(t *testing.T) {
 	assert.Equal(t, uint(0), result[0].Logs[0].TxIndex) // should be sorted
 	assert.Equal(t, uint(1), result[0].Logs[1].TxIndex)
 }
+
+// TestPackLogsOrdersByLogIndexWithinTransaction covers logs emitted by the same transaction
+// (same TxIndex, distinct logIndex) — e.g. bulkRegisterValidator, whose per-owner nonces require
+// in-order processing. They must be packed in logIndex order, not left in the arbitrary order a
+// non-stable sort by (block, tx) would leave them. Input is deliberately shuffled.
+func TestPackLogsOrdersByLogIndexWithinTransaction(t *testing.T) {
+	logs := []types.Log{
+		{BlockNumber: 5, TxIndex: 2, Index: 11},
+		{BlockNumber: 5, TxIndex: 2, Index: 9},
+		{BlockNumber: 5, TxIndex: 0, Index: 3}, // earlier tx in the same block
+		{BlockNumber: 5, TxIndex: 2, Index: 10},
+	}
+
+	result := PackLogs(logs)
+	assert.Len(t, result, 1)
+	assert.Equal(t, uint64(5), result[0].BlockNumber)
+
+	gotIndexes := make([]uint, 0, len(result[0].Logs))
+	for _, l := range result[0].Logs {
+		gotIndexes = append(gotIndexes, l.Index)
+	}
+	assert.Equal(t, []uint{3, 9, 10, 11}, gotIndexes)
+}