diff --git a/libkworkspace/CMakeLists.txt b/libkworkspace/CMakeLists.txt
--- a/libkworkspace/CMakeLists.txt
+++ b/libkworkspace/CMakeLists.txt
@@ -3,6 +3,7 @@
                         kworkspace.cpp
                         sessionmanagement.cpp
                         sessionmanagementbackend.cpp
+                        updatelaunchenvjob.cpp
    )
 
 add_definitions(-DTRANSLATION_DOMAIN=\"libkworkspace\")
@@ -12,9 +13,11 @@
 
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
 
+qt5_add_dbus_interface(kworkspace_LIB_SRCS ${KINIT_DBUS_INTERFACES_DIR}/kf5_org.kde.KLauncher.xml klauncher_interface)
 qt5_add_dbus_interface(kworkspace_LIB_SRCS ${KSCREENLOCKER_DBUS_INTERFACES_DIR}/kf5_org.freedesktop.ScreenSaver.xml screenlocker_interface )
 qt5_add_dbus_interface(kworkspace_LIB_SRCS ${KSCREENLOCKER_DBUS_INTERFACES_DIR}/org.kde.screensaver.xml kscreenlocker_interface )
 qt5_add_dbus_interface(kworkspace_LIB_SRCS ${plasma-workspace_SOURCE_DIR}/ksmserver/org.kde.LogoutPrompt.xml logoutprompt_interface)
+qt5_add_dbus_interface(kworkspace_LIB_SRCS ${plasma-workspace_SOURCE_DIR}/startkde/plasma-session/org.kde.Startup.xml startup_interface)
 qt5_add_dbus_interface(kworkspace_LIB_SRCS ${plasma-workspace_SOURCE_DIR}/startkde/plasma-session/org.kde.Shutdown.xml shutdown_interface)
 
 set_source_files_properties("${CMAKE_CURRENT_SOURCE_DIR}/org.freedesktop.login1.Manager.xml"
@@ -78,6 +81,7 @@
 install( FILES kdisplaymanager.h
                kworkspace.h
                sessionmanagement.h
+               updatelaunchenvjob.h
                ${CMAKE_CURRENT_BINARY_DIR}/config-libkworkspace.h
                ${CMAKE_CURRENT_BINARY_DIR}/kworkspace_export.h
          DESTINATION ${KDE_INSTALL_INCLUDEDIR}/kworkspace5 COMPONENT Devel )
diff --git a/libkworkspace/updatelaunchenvjob.h b/libkworkspace/updatelaunchenvjob.h
new file mode 100644
--- /dev/null
+++ b/libkworkspace/updatelaunchenvjob.h
@@ -0,0 +1,54 @@
+/*
+   Copyright (C) 2020 Kai Uwe Broulik <kde@broulik.de>
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the Lesser GNU General Public
+   License as published by the Free Software Foundation; either
+   version 2 of the License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    General Public License for more details.
+
+   You should have received a copy of the Lesser GNU General Public License
+   along with this program; see the file COPYING.  If not, write to
+   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.
+*/
+
+#pragma once
+
+#include "kworkspace_export.h"
+
+#include <KJob>
+
+class QString;
+
+/**
+ * Job for updating the launch environment.
+ *
+ * This job adds or updates an environment variable in process environment that will be used
+ * anywhere a process is launched, e.g. DBus-activation environment, KLauncher environment, etc.
+ *
+ * @code
+ * UpdateLaunchEnvJob("XCURSOR_THEME", "NewTheme");
+ * @endcode
+ *
+ * @since 5.19
+ */
+class KWORKSPACE_EXPORT UpdateLaunchEnvJob : public KJob
+{
+    Q_OBJECT
+
+public:
+    explicit UpdateLaunchEnvJob(const QString &varName, const QString &value);
+    ~UpdateLaunchEnvJob() override;
+
+    void start() override;
+
+private:
+    class Private;
+    Private * const d;
+
+};
diff --git a/libkworkspace/updatelaunchenvjob.cpp b/libkworkspace/updatelaunchenvjob.cpp
new file mode 100644
--- /dev/null
+++ b/libkworkspace/updatelaunchenvjob.cpp
@@ -0,0 +1,101 @@
+/*
+   Copyright (C) 2020 Kai Uwe Broulik <kde@broulik.de>
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the Lesser GNU General Public
+   License as published by the Free Software Foundation; either
+   version 2 of the License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    General Public License for more details.
+
+   You should have received a copy of the Lesser GNU General Public License
+   along with this program; see the file COPYING.  If not, write to
+   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.
+*/
+
+#include "updatelaunchenvjob.h"
+
+#include <klauncher_interface.h>
+#include <startup_interface.h>
+
+class Q_DECL_HIDDEN UpdateLaunchEnvJob::Private
+{
+public:
+    explicit Private(UpdateLaunchEnvJob *q);
+    void monitorReply(const QDBusPendingReply<> &reply);
+
+    UpdateLaunchEnvJob *q;
+    QString varName;
+    QString value;
+    int pendingReplies = 0;
+};
+
+UpdateLaunchEnvJob::Private::Private(UpdateLaunchEnvJob *q)
+    : q(q)
+{
+
+}
+
+void UpdateLaunchEnvJob::Private::monitorReply(const QDBusPendingReply<> &reply)
+{
+    ++pendingReplies;
+
+    auto *watcher = new QDBusPendingCallWatcher(reply, q);
+    QObject::connect(watcher, &QDBusPendingCallWatcher::finished, q, [this](QDBusPendingCallWatcher *watcher) {
+        watcher->deleteLater();
+        --pendingReplies;
+
+        if (pendingReplies == 0) {
+            q->emitResult();
+        }
+    });
+}
+
+UpdateLaunchEnvJob::UpdateLaunchEnvJob(const QString &varName, const QString &value)
+    : d(new Private(this))
+{
+    d->varName = varName;
+    d->value = value;
+}
+
+UpdateLaunchEnvJob::~UpdateLaunchEnvJob()
+{
+    delete d;
+}
+
+void UpdateLaunchEnvJob::start()
+{
+    // KLauncher
+    org::kde::KLauncher klauncher(QStringLiteral("org.kde.klauncher5"),
+                                  QStringLiteral("/KLauncher"),
+                                  QDBusConnection::sessionBus());
+    auto klauncherReply = klauncher.setLaunchEnv(d->varName, d->value);
+    d->monitorReply(klauncherReply);
+
+    // plasma-session
+    org::kde::Startup startup(QStringLiteral("org.kde.Startup"),
+                              QStringLiteral("/Startup"),
+                              QDBusConnection::sessionBus());
+    auto startupReply = startup.updateLaunchEnv(d->varName, d->value);
+    d->monitorReply(startupReply);
+
+    // DBus-activation environment
+    qDBusRegisterMetaType<QMap<QString, QString>>();
+    const QMap<QString, QString> dbusActivationEnv{
+        {d->varName, d->value}
+    };
+
+    QDBusMessage dbusActivationMsg = QDBusMessage::createMethodCall(QStringLiteral("org.freedesktop.DBus"),
+                                                                    QStringLiteral("/org/freedesktop/DBus"),
+                                                                    QStringLiteral("org.freedesktop.DBus"),
+                                                                    QStringLiteral("UpdateActivationEnvironment"));
+    dbusActivationMsg.setArguments({QVariant::fromValue(dbusActivationEnv)});
+
+    auto dbusActivationReply = QDBusConnection::sessionBus().asyncCall(dbusActivationMsg);
+    d->monitorReply(dbusActivationReply);
+}
+