diff --git a/src/corelib/CMakeLists.txt b/src/corelib/CMakeLists.txt
index b2d51349a93..96e385a8a72 100644
--- a/src/corelib/CMakeLists.txt
+++ b/src/corelib/CMakeLists.txt
@@ -135,7 +135,7 @@ qt_internal_add_module(Core
         io/qiodevicebase.h
         io/qipaddress.cpp io/qipaddress_p.h
         io/qlockfile.cpp io/qlockfile.h io/qlockfile_p.h
-        io/qloggingcategory.cpp io/qloggingcategory.h
+        io/qloggingcategory.cpp io/qloggingcategory.h io/qloggingcategory_p.h
         io/qloggingregistry.cpp io/qloggingregistry_p.h
         io/qnoncontiguousbytedevice.cpp io/qnoncontiguousbytedevice_p.h
         io/qresource.cpp io/qresource.h io/qresource_p.h
diff --git a/src/corelib/global/qlogging.cpp b/src/corelib/global/qlogging.cpp
index 12d9422daad..97c7e70e386 100644
--- a/src/corelib/global/qlogging.cpp
+++ b/src/corelib/global/qlogging.cpp
@@ -953,7 +953,7 @@ QDebug QMessageLogger::fatal(QMessageLogger::CategoryFunction catFunc) const
 
 static bool isDefaultCategory(const char *category)
 {
-    return !category || strcmp(category, "default") == 0;
+    return !category || strcmp(category, QLoggingRegistry::defaultCategoryName) == 0;
 }
 
 /*!
diff --git a/src/corelib/io/qloggingcategory.cpp b/src/corelib/io/qloggingcategory.cpp
index d60abba70d5..4ce2bf0c091 100644
--- a/src/corelib/io/qloggingcategory.cpp
+++ b/src/corelib/io/qloggingcategory.cpp
@@ -2,13 +2,11 @@
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
 #include "qloggingcategory.h"
+#include "qloggingcategory_p.h"
 #include "qloggingregistry_p.h"
 
 QT_BEGIN_NAMESPACE
 
-const char qtDefaultCategoryName[] = "default";
-Q_GLOBAL_STATIC(QLoggingCategory, qtDefaultCategory, qtDefaultCategoryName)
-
 /*!
     \class QLoggingCategory
     \inmodule QtCore
@@ -170,17 +168,10 @@ Q_GLOBAL_STATIC(QLoggingCategory, qtDefaultCategory, qtDefaultCategoryName)
     \since 5.4
 */
 QLoggingCategory::QLoggingCategory(const char *category, QtMsgType enableForLevel)
-    : d(nullptr),
-      name(nullptr)
+    : QLoggingCategory(UnregisteredInitialization{},
+                       category ? category : QLoggingRegistry::defaultCategoryName)
 {
-    enabled.storeRelaxed(0x01010101);   // enabledDebug = enabledWarning = enabledCritical = true;
-
-    if (category)
-        name = category;
-    else
-        name = qtDefaultCategoryName;
-
-    if (QLoggingRegistry *reg = QLoggingRegistry::instance())
+   if (QLoggingRegistry *reg = QLoggingRegistry::instance())
         reg->registerCategory(this, enableForLevel);
 }
 
@@ -189,6 +180,9 @@ QLoggingCategory::QLoggingCategory(const char *category, QtMsgType enableForLeve
 */
 QLoggingCategory::~QLoggingCategory()
 {
+    // Note: this destructor is never called for the defaultCategory(), so it
+    // is always registered. If we ever need to free memory, make
+    // QLoggingRegistry do it.
     if (QLoggingRegistry *reg = QLoggingRegistry::instance())
         reg->unregisterCategory(this);
 }
@@ -309,7 +303,7 @@ void QLoggingCategory::setEnabled(QtMsgType type, bool enable)
  */
 QLoggingCategory *QLoggingCategory::defaultCategory()
 {
-    return qtDefaultCategory();
+    return QLoggingRegistry::defaultCategory();
 }
 
 /*!
diff --git a/src/corelib/io/qloggingcategory.h b/src/corelib/io/qloggingcategory.h
index f2fdee24e7b..5a4ecf59e33 100644
--- a/src/corelib/io/qloggingcategory.h
+++ b/src/corelib/io/qloggingcategory.h
@@ -52,6 +52,10 @@ private:
         QBasicAtomicInt enabled;
     };
     Q_DECL_UNUSED_MEMBER bool placeholder[4]; // reserved for future use
+
+    QT_DEFINE_TAG_STRUCT(UnregisteredInitialization);
+    explicit constexpr QLoggingCategory(UnregisteredInitialization, const char *category) noexcept;
+    friend class QLoggingRegistry;
 };
 
 namespace { // allow different TUs to have different QT_NO_xxx_OUTPUT
diff --git a/src/corelib/io/qloggingcategory_p.h b/src/corelib/io/qloggingcategory_p.h
new file mode 100644
index 00000000000..46da266db0a
--- /dev/null
+++ b/src/corelib/io/qloggingcategory_p.h
@@ -0,0 +1,35 @@
+// Copyright (C) 2025 Intel Corporation.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef QLOGGINGCATEGORY_P_H
+#define QLOGGINGCATEGORY_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of a number of Qt sources files.  This header file may change from
+// version to version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qloggingcategory.h>
+#include <QtCore/private/qglobal_p.h>
+
+QT_BEGIN_NAMESPACE
+
+// enabledDebug = enabledWarning = enabledCritical = enableInfo = true;
+static constexpr int DefaultLoggingCategoryEnabledValue = 0x01010101;
+
+constexpr inline
+QLoggingCategory::QLoggingCategory(UnregisteredInitialization, const char *category) noexcept
+    : name(category),
+      enabled(DefaultLoggingCategoryEnabledValue),
+      placeholder{}
+{}
+
+QT_END_NAMESPACE
+
+#endif // QLOGGINGCATEGORY_P_H
diff --git a/src/corelib/io/qloggingregistry.cpp b/src/corelib/io/qloggingregistry.cpp
index da8ed80ff16..ece58cfa87e 100644
--- a/src/corelib/io/qloggingregistry.cpp
+++ b/src/corelib/io/qloggingregistry.cpp
@@ -27,6 +27,7 @@ QT_BEGIN_NAMESPACE
 using namespace Qt::StringLiterals;
 
 Q_GLOBAL_STATIC(QLoggingRegistry, qtLoggingRegistry)
+alignas(QLoggingCategory) static unsigned char defaultLoggingCategory[sizeof(QLoggingCategory)];
 
 /*!
     \internal
@@ -227,6 +228,14 @@ void QLoggingSettingsParser::parseNextLine(QStringView line)
 QLoggingRegistry::QLoggingRegistry()
     : categoryFilter(defaultCategoryFilter)
 {
+    using U = QLoggingCategory::UnregisteredInitialization;
+    Q_ASSERT_X(!self, "QLoggingRegistry", "Singleton recreated");
+    self = this;
+
+    // can't use std::construct_at here - private constructor
+    auto cat = new (defaultLoggingCategory) QLoggingCategory(U{}, defaultCategoryName);
+    categories.emplace(cat, QtDebugMsg);
+
 #if defined(Q_OS_ANDROID)
     // Unless QCoreApplication has been constructed we can't be sure that
     // we are on Qt's main thread. If we did allow logging here, we would
@@ -424,6 +433,18 @@ QLoggingRegistry *QLoggingRegistry::instance()
     return qtLoggingRegistry();
 }
 
+QLoggingCategory *QLoggingRegistry::defaultCategory()
+{
+    // Initialize the defaultLoggingCategory global static, if necessary. Note
+    // how it remains initialized forever, even if the QLoggingRegistry
+    // instance() is destroyed.
+    instance();
+
+    // std::launder() to be on the safe side, but it's unnecessary because the
+    // object is never recreated.
+    return std::launder(reinterpret_cast<QLoggingCategory *>(defaultLoggingCategory));
+}
+
 /*!
     \internal
     Updates category settings according to rules.
@@ -432,7 +453,7 @@ QLoggingRegistry *QLoggingRegistry::instance()
 */
 void QLoggingRegistry::defaultCategoryFilter(QLoggingCategory *cat)
 {
-    const QLoggingRegistry *reg = QLoggingRegistry::instance();
+    const QLoggingRegistry *reg = self;
     Q_ASSERT(reg->categories.contains(cat));
     QtMsgType enableForLevel = reg->categories.value(cat);
 
diff --git a/src/corelib/io/qloggingregistry_p.h b/src/corelib/io/qloggingregistry_p.h
index 28d64b7cf2c..0716a33ebda 100644
--- a/src/corelib/io/qloggingregistry_p.h
+++ b/src/corelib/io/qloggingregistry_p.h
@@ -15,8 +15,7 @@
 // We mean it.
 //
 
-#include <QtCore/private/qglobal_p.h>
-#include <QtCore/qloggingcategory.h>
+#include <QtCore/private/qloggingcategory_p.h>
 #include <QtCore/qlist.h>
 #include <QtCore/qhash.h>
 #include <QtCore/qmutex.h>
@@ -116,8 +115,12 @@ public:
 
     Q_CORE_EXPORT static QLoggingRegistry *instance();
 
+    static constexpr const char defaultCategoryName[] = "default";
+    static QLoggingCategory *defaultCategory();
+
 private:
     Q_AUTOTEST_EXPORT void updateRules();
+    static inline QLoggingRegistry *self = nullptr;
 
     static void defaultCategoryFilter(QLoggingCategory *category);