diff --git a/src/corelib/text/qlocale.cpp b/src/corelib/text/qlocale.cpp
index dd72677442a..42fdb49474e 100644
--- a/src/corelib/text/qlocale.cpp
+++ b/src/corelib/text/qlocale.cpp
@@ -3563,7 +3563,7 @@ Qt::LayoutDirection QLocale::textDirection() const
 */
 QString QLocale::toUpper(const QString &str) const
 {
-#if !defined(QT_BOOTSTRAPPED) && (QT_CONFIG(icu) || defined(Q_OS_WIN))
+#if !defined(QT_BOOTSTRAPPED) && (QT_CONFIG(icu) || defined(Q_OS_WIN) || defined(Q_OS_APPLE))
     bool ok = true;
     QString result = d->toUpper(str, &ok);
     if (ok)
@@ -3587,7 +3587,7 @@ QString QLocale::toUpper(const QString &str) const
 */
 QString QLocale::toLower(const QString &str) const
 {
-#if !defined(QT_BOOTSTRAPPED) && (QT_CONFIG(icu) || defined(Q_OS_WIN))
+#if !defined(QT_BOOTSTRAPPED) && (QT_CONFIG(icu) || defined(Q_OS_WIN) || defined(Q_OS_APPLE))
     bool ok = true;
     const QString result = d->toLower(str, &ok);
     if (ok)
diff --git a/src/corelib/text/qlocale_mac.mm b/src/corelib/text/qlocale_mac.mm
index ff1abcd0447..87f20310980 100644
--- a/src/corelib/text/qlocale_mac.mm
+++ b/src/corelib/text/qlocale_mac.mm
@@ -697,4 +697,40 @@ QVariant QSystemLocale::query(QueryType type, QVariant &&in) const
 
 #endif // QT_NO_SYSTEMLOCALE
 
+#if !QT_CONFIG(icu)
+
+static QString localeConvertString(const QByteArray &localeID, const QString &str, bool *ok,
+                                   bool toLowerCase)
+{
+    QMacAutoReleasePool pool;
+    Q_ASSERT(ok);
+    NSString *localestring = [[NSString alloc] initWithData:localeID.toNSData()
+                                                   encoding:NSUTF8StringEncoding];
+    NSLocale *locale = [NSLocale localeWithLocaleIdentifier:localestring];
+    if (!locale) {
+        *ok = false;
+        return QString();
+    }
+    *ok = true;
+    NSString *nsstring = str.toNSString();
+    if (toLowerCase)
+        nsstring = [nsstring lowercaseStringWithLocale:locale];
+    else
+        nsstring = [nsstring uppercaseStringWithLocale:locale];
+
+    return QString::fromNSString(nsstring);
+}
+
+QString QLocalePrivate::toLower(const QString &str, bool *ok) const
+{
+    return localeConvertString(bcp47Name('-'), str, ok, true);
+}
+
+QString QLocalePrivate::toUpper(const QString &str, bool *ok) const
+{
+    return localeConvertString(bcp47Name('-'), str, ok, false);
+}
+
+#endif
+
 QT_END_NAMESPACE
diff --git a/src/corelib/text/qlocale_p.h b/src/corelib/text/qlocale_p.h
index 7434734dec1..4833c0b424c 100644
--- a/src/corelib/text/qlocale_p.h
+++ b/src/corelib/text/qlocale_p.h
@@ -552,10 +552,8 @@ public:
 
     [[nodiscard]] QLocale::MeasurementSystem measurementSystem() const;
 
-#if QT_CONFIG(icu) || (defined(Q_OS_WIN) && !defined(QT_BOOTSTRAPPED))
     [[nodiscard]] QString toUpper(const QString &str, bool *ok) const;
     [[nodiscard]] QString toLower(const QString &str, bool *ok) const;
-#endif
 
     // System locale has an m_data all its own; all others have m_data = locale_data + m_index
     const QLocaleData *const m_data;
diff --git a/tests/auto/corelib/text/qlocale/tst_qlocale.cpp b/tests/auto/corelib/text/qlocale/tst_qlocale.cpp
index 0040e1b3783..fba1fd01437 100644
--- a/tests/auto/corelib/text/qlocale/tst_qlocale.cpp
+++ b/tests/auto/corelib/text/qlocale/tst_qlocale.cpp
@@ -161,7 +161,7 @@ private slots:
     void lcsToCode();
     void codeToLcs();
 
-#if QT_CONFIG(icu) || defined(Q_OS_WIN)
+#if QT_CONFIG(icu) || defined(Q_OS_WIN) || defined(Q_OS_APPLE)
     void toLowerUpper_data();
     void toLowerUpper();
 
@@ -4777,7 +4777,7 @@ void tst_QLocale::codeToLcs()
     QCOMPARE(QLocale::codeToScript(QString("Hans")), QLocale::SimplifiedHanScript);
 }
 
-#if QT_CONFIG(icu) || defined(Q_OS_WIN)
+#if QT_CONFIG(icu) || defined(Q_OS_WIN) || defined(Q_OS_APPLE)
 void tst_QLocale::toLowerUpper_data()
 {
     QTest::addColumn<QLocale>("locale");