diff --git a/sqlglot/dialects/duckdb.py b/sqlglot/dialects/duckdb.py
index 05761e4fd6..f61cd2c4d5 100644
--- a/sqlglot/dialects/duckdb.py
+++ b/sqlglot/dialects/duckdb.py
@@ -1166,18 +1166,26 @@ def length_sql(self, expression: exp.Length) -> str:
             return self.sql(case)
 
         def lower_sql(self, expression: exp.Lower) -> str:
+            return self._case_conversion_sql(expression, "LOWER")
+
+        def upper_sql(self, expression: exp.Upper) -> str:
+            return self._case_conversion_sql(expression, "UPPER")
+
+        def _case_conversion_sql(
+            self, expression: t.Union[exp.Lower, exp.Upper], func_name: str
+        ) -> str:
             arg = expression.this
             if arg.type and not arg.is_type(exp.DataType.Type.VARCHAR, exp.DataType.Type.UNKNOWN):
                 expression.this.replace(exp.cast(expression.this, exp.DataType.Type.VARCHAR))
 
-            lower_sql = self.func("LOWER", expression.this)
+            result_sql = self.func(func_name, expression.this)
 
             is_binary = expression.is_type(exp.DataType.Type.BINARY)
             if is_binary:
                 blob = exp.DataType.build("BLOB", dialect="duckdb")
-                lower_sql = self.sql(exp.Cast(this=lower_sql, to=blob))
+                result_sql = self.sql(exp.Cast(this=result_sql, to=blob))
 
-            return lower_sql
+            return result_sql
 
         def objectinsert_sql(self, expression: exp.ObjectInsert) -> str:
             this = expression.this
diff --git a/tests/dialects/test_bigquery.py b/tests/dialects/test_bigquery.py
index 00a720b39d..8249894f88 100644
--- a/tests/dialects/test_bigquery.py
+++ b/tests/dialects/test_bigquery.py
@@ -900,6 +900,20 @@ def test_bigquery(self):
                 "trino": "LOWER(TO_HEX(x))",
             },
         )
+
+        sql = "UPPER(CAST('hello' AS BYTES))"
+        expr = self.parse_one(sql)
+        qualified = qualify(expr, dialect="bigquery")
+        annotated = annotate_types(qualified, dialect="bigquery")
+        self.assertEqual(
+            annotated.sql("duckdb"), "CAST(UPPER(CAST(CAST('hello' AS BLOB) AS TEXT)) AS BLOB)"
+        )
+
+        sql = "UPPER('hello')"
+        expr = self.parse_one(sql)
+        annotated = annotate_types(expr, dialect="bigquery")
+        self.assertEqual(annotated.sql("duckdb"), "UPPER('hello')")
+
         self.validate_all(
             "UPPER(TO_HEX(x))",
             read={
diff --git a/tests/dialects/test_duckdb.py b/tests/dialects/test_duckdb.py
index f59c680d67..e6520e50bd 100644
--- a/tests/dialects/test_duckdb.py
+++ b/tests/dialects/test_duckdb.py
@@ -1166,6 +1166,9 @@ def test_duckdb(self):
         self.assertEqual(
             annotate_types(self.parse_one("LOWER('HELLO')")).sql("duckdb"), "LOWER('HELLO')"
         )
+        self.assertEqual(
+            annotate_types(self.parse_one("UPPER('hello')")).sql("duckdb"), "UPPER('hello')"
+        )
 
     def test_array_index(self):
         with self.assertLogs(helper_logger) as cm: