diff --git a/pkg/sql/colexec/colbuilder/execplan.go b/pkg/sql/colexec/colbuilder/execplan.go
index 2d6b8b34f267..8ba8120f54a6 100644
--- a/pkg/sql/colexec/colbuilder/execplan.go
+++ b/pkg/sql/colexec/colbuilder/execplan.go
@@ -2727,6 +2727,7 @@ func planProjectionExpr(
 		resultIdx = len(typs)
 		// The projection result will be outputted to a new column which is
 		// appended to the input batch.
+		// TODO(#127814): We may need to handle the case when the left is DNull.
 		op, err = colexecprojconst.GetProjectionLConstOperator(
 			allocator, typs, left.ResolvedType(), outputType, projOp, input,
 			rightIdx, lConstArg, resultIdx, evalCtx, binOp, cmpExpr, calledOnNullInput,
@@ -2769,7 +2770,12 @@ func planProjectionExpr(
 			// The projection result will be outputted to a new column which is
 			// appended to the input batch.
 			resultIdx = len(typs)
-			if isCmpProjOp {
+			if !calledOnNullInput && right == tree.DNull {
+				// If the right is NULL and the operator is not called on NULL,
+				// simply project NULL.
+				op = colexecbase.NewConstNullOp(allocator, input, resultIdx)
+			} else if isCmpProjOp {
+				// Use optimized operators for special cases.
 				switch cmpProjOp.Symbol {
 				case treecmp.Like, treecmp.NotLike, treecmp.ILike, treecmp.NotILike:
 					negate, caseInsensitive := examineLikeOp(cmpProjOp)
diff --git a/pkg/sql/logictest/testdata/logic_test/subquery b/pkg/sql/logictest/testdata/logic_test/subquery
index a08d12fd75ad..460f426f1a2b 100644
--- a/pkg/sql/logictest/testdata/logic_test/subquery
+++ b/pkg/sql/logictest/testdata/logic_test/subquery
@@ -1039,4 +1039,18 @@ LEFT JOIN LATERAL (
 row-1  row-1  {row-1}  1
 row-2  row-2  {row-2}  1
 
-subtest end
+# Regression test for #127814. The vectorized engine should correctly project
+# expressions operating on NULL.
+statement ok
+CREATE TABLE t127814_empty (i INT)
+
+statement ok
+CREATE TABLE t127814 (o OID)
+
+statement ok
+INSERT INTO t127814 VALUES (0)
+
+query B
+SELECT o NOT IN ((SELECT NULL FROM t127814_empty),) FROM t127814
+----
+NULL