diff --git a/pkg/sql/logictest/testdata/logic_test/udf b/pkg/sql/logictest/testdata/logic_test/udf
index ec378d4cc950..22e0278074c6 100644
--- a/pkg/sql/logictest/testdata/logic_test/udf
+++ b/pkg/sql/logictest/testdata/logic_test/udf
@@ -3044,3 +3044,50 @@ query I
 SELECT count(descriptor) FROM system.descriptor WHERE id = $dropped_fn_id;
 ----
 0
+
+subtest udt_alter
+
+statement ok
+CREATE TABLE t_alter (
+  a INT PRIMARY KEY,
+  b INT
+)
+
+statement ok
+CREATE FUNCTION f_rtbl() RETURNS t_alter LANGUAGE SQL AS 'SELECT 1, 2;'
+
+query T
+SELECT f_rtbl();
+----
+(1,2)
+
+statement ok
+ALTER TABLE t_alter DROP COLUMN b;
+
+statement error pq: return type mismatch in function declared to return t_alter
+SELECT f_rtbl();
+
+statement ok
+ALTER TABLE t_alter ADD COLUMN b INT;
+
+query T
+SELECT f_rtbl();
+----
+(1,2)
+
+statement ok
+SET enable_experimental_alter_column_type_general=true
+
+statement ok
+ALTER TABLE t_alter ALTER b TYPE FLOAT;
+
+statement error pq: return type mismatch in function declared to return t_alter
+SELECT f_rtbl();
+
+statement ok
+ALTER TABLE t_alter ALTER b TYPE INT;
+
+query T
+SELECT f_rtbl();
+----
+(1,2)
diff --git a/pkg/sql/logictest/testdata/logic_test/udf_star b/pkg/sql/logictest/testdata/logic_test/udf_star
index 3f1f3644bcc3..e8bc1e7fc047 100644
--- a/pkg/sql/logictest/testdata/logic_test/udf_star
+++ b/pkg/sql/logictest/testdata/logic_test/udf_star
@@ -173,16 +173,20 @@ SELECT f_allcolsel_alias()
 ----
 (1,2)
 
+# Return an error after adding a column when the table is used as the return
+# type. Note that this behavior is ok for late binding.
 statement ok
 ALTER TABLE t_twocol ADD COLUMN c INT DEFAULT 5;
 
-# TODO(#95558): With early binding, postgres returns an error after adding a
-# column when the table is used as the return type. Note that this behavior is
-# ok for late binding.
-query T
+statement error pq: return type mismatch in function declared to return t_twocol
+SELECT f_unqualified_twocol()
+
+# Dropping the new column renders the function usable again.
+statement ok
+ALTER TABLE t_twocol DROP COLUMN c;
+
+statement ok
 SELECT f_unqualified_twocol()
-----
-(1,2)
 
 # Altering a column type is not allowed in postgres or CRDB.
 statement error pq: cannot alter type of column "b" because function "f_unqualified_twocol" depends on it
diff --git a/pkg/sql/opt/optbuilder/scalar.go b/pkg/sql/opt/optbuilder/scalar.go
index 7816cfa430b7..d83abdecf4b9 100644
--- a/pkg/sql/opt/optbuilder/scalar.go
+++ b/pkg/sql/opt/optbuilder/scalar.go
@@ -688,6 +688,22 @@ func (b *Builder) buildUDF(
 			// ConvertUDFToSubquery.
 			physProps.Ordering = props.OrderingChoice{}
 
+			// Validate that user defined return types match the original return types
+			// defined in the function.
+			rtyp := f.ResolvedType()
+			if rtyp.UserDefined() {
+				funcReturnType, err := tree.ResolveType(b.ctx,
+					&tree.OIDTypeReference{OID: rtyp.Oid()}, b.semaCtx.TypeResolver)
+				if err != nil {
+					panic(err)
+				}
+				if !funcReturnType.Equivalent(rtyp) {
+					panic(pgerror.Newf(
+						pgcode.InvalidFunctionDefinition,
+						"return type mismatch in function declared to return %s", rtyp.Name()))
+				}
+			}
+
 			// If there are multiple output columns, we must combine them into a
 			// tuple - only a single column can be returned from a UDF.
 			if cols := physProps.Presentation; len(cols) > 1 {