diff --git a/tns-core-modules/application/application-common.ts b/tns-core-modules/application/application-common.ts
@@ -42,7 +42,7 @@ import {
 } from "./application";
 
 import { CLASS_PREFIX, pushToRootViewCssClasses, removeFromRootViewCssClasses } from "../css/system-classes";
-import { DeviceOrientation } from "../ui/enums/enums";
+import { DeviceOrientation, SystemAppearance } from "../ui/enums/enums";
 
 export { UnhandledErrorEventData, DiscardedErrorEventData, CssChangedEventData, LoadAppCSSEventData };
 
@@ -55,13 +55,19 @@ export const lowMemoryEvent = "lowMemory";
 export const uncaughtErrorEvent = "uncaughtError";
 export const discardedErrorEvent = "discardedError";
 export const orientationChangedEvent = "orientationChanged";
+export const systemAppearanceChangedEvent = "systemAppearanceChanged";
 
 const ORIENTATION_CSS_CLASSES = [
     `${CLASS_PREFIX}${DeviceOrientation.portrait}`,
     `${CLASS_PREFIX}${DeviceOrientation.landscape}`,
     `${CLASS_PREFIX}${DeviceOrientation.unknown}`
 ];
 
+const SYSTEM_APPEARANCE_CSS_CLASSES = [
+    `${CLASS_PREFIX}${SystemAppearance.light}`,
+    `${CLASS_PREFIX}${SystemAppearance.dark}`
+];
+
 let cssFile: string = "./app.css";
 
 let resources: any = {};
@@ -126,17 +132,30 @@ export function loadAppCss(): void {
     }
 }
 
+function applyCssClass(rootView: View, cssClass: string) {
+    pushToRootViewCssClasses(cssClass);
+    rootView.cssClasses.add(cssClass);
+}
+
+function removeCssClass(rootView: View, cssClass: string) {
+    removeFromRootViewCssClasses(cssClass);
+    rootView.cssClasses.delete(cssClass);
+}
+
 export function orientationChanged(rootView: View, newOrientation: "portrait" | "landscape" | "unknown"): void {
     const newOrientationCssClass = `${CLASS_PREFIX}${newOrientation}`;
     if (!rootView.cssClasses.has(newOrientationCssClass)) {
-        const removeCssClass = (c: string) => {
-            removeFromRootViewCssClasses(c);
-            rootView.cssClasses.delete(c);
-        };
-
-        ORIENTATION_CSS_CLASSES.forEach(c => removeCssClass(c));
-        pushToRootViewCssClasses(newOrientationCssClass);
-        rootView.cssClasses.add(newOrientationCssClass);
+        ORIENTATION_CSS_CLASSES.forEach(cssClass => removeCssClass(rootView, cssClass));
+        applyCssClass(rootView, newOrientationCssClass);
+        rootView._onCssStateChange();
+    }
+}
+
+export function systemAppearanceChanged(rootView: View, newSystemAppearance: "dark" | "light"): void {
+    const newSystemAppearanceCssClass = `${CLASS_PREFIX}${newSystemAppearance}`;
+    if (!rootView.cssClasses.has(newSystemAppearanceCssClass)) {
+        SYSTEM_APPEARANCE_CSS_CLASSES.forEach(cssClass => removeCssClass(rootView, cssClass));
+        applyCssClass(rootView, newSystemAppearanceCssClass);
         rootView._onCssStateChange();
     }
 }

diff --git a/tns-core-modules/application/application.android.ts b/tns-core-modules/application/application.android.ts
@@ -9,12 +9,14 @@ import {
     AndroidApplication as AndroidApplicationDefinition,
     ApplicationEventData,
     CssChangedEventData,
-    OrientationChangedEventData
+    OrientationChangedEventData,
+    SystemAppearanceChangedEventData
 } from ".";
 
 import {
     displayedEvent, hasListeners, livesync, lowMemoryEvent, notify, Observable, on,
-    orientationChanged, orientationChangedEvent, setApplication, suspendEvent
+    orientationChanged, orientationChangedEvent, setApplication, suspendEvent,
+    systemAppearanceChanged, systemAppearanceChangedEvent
 } from "./application-common";
 
 import { profile } from "../profiling";
@@ -51,6 +53,7 @@ export class AndroidApplication extends Observable implements AndroidApplication
     public static activityRequestPermissionsEvent = ActivityRequestPermissions;
 
     private _orientation: "portrait" | "landscape" | "unknown";
+    private _systemAppearance: "light" | "dark";
     public paused: boolean;
     public nativeApp: android.app.Application;
     public context: android.content.Context;
@@ -93,9 +96,8 @@ export class AndroidApplication extends Observable implements AndroidApplication
         if (!this._orientation) {
             const resources = this.context.getResources();
             const configuration = <android.content.res.Configuration>resources.getConfiguration();
-            const orientation = configuration.orientation;
 
-            this._orientation = getOrientationValue(orientation);
+            this._orientation = getOrientationValue(configuration);
         }
 
         return this._orientation;
@@ -105,6 +107,21 @@ export class AndroidApplication extends Observable implements AndroidApplication
         this._orientation = value;
     }
 
+    get systemAppearance(): "light" | "dark" {
+        if (!this._systemAppearance) {
+            const resources = this.context.getResources();
+            const configuration = <android.content.res.Configuration>resources.getConfiguration();
+
+            this._systemAppearance = getSystemAppearanceValue(configuration);
+        }
+
+        return this._systemAppearance;
+    }
+
+    set systemAppearance(value: "light" | "dark") {
+        this._systemAppearance = value;
+    }
+
     public registerBroadcastReceiver(intentFilter: string, onReceiveCallback: (context: android.content.Context, intent: android.content.Intent) => void) {
         ensureBroadCastReceiverClass();
         const that = this;
@@ -131,6 +148,7 @@ export class AndroidApplication extends Observable implements AndroidApplication
         }
     }
 }
+
 export interface AndroidApplication {
     on(eventNames: string, callback: (data: AndroidActivityEventData) => void, thisArg?: any);
     on(event: "activityCreated", callback: (args: AndroidActivityBundleEventData) => void, thisArg?: any);
@@ -252,12 +270,9 @@ export function orientation(): "portrait" | "landscape" | "unknown" {
     return androidApp.orientation;
 }
 
-on(orientationChangedEvent, (args: OrientationChangedEventData) => {
-    const rootView = getRootView();
-    if (rootView) {
-        orientationChanged(rootView, args.newValue);
-    }
-});
+export function systemAppearance(): "dark" | "light" {
+    return androidApp.systemAppearance;
+}
 
 global.__onLiveSync = function __onLiveSync(context?: ModuleContext) {
     if (androidApp && androidApp.paused) {
@@ -268,7 +283,9 @@ global.__onLiveSync = function __onLiveSync(context?: ModuleContext) {
     livesync(rootView, context);
 };
 
-function getOrientationValue(orientation: number): "portrait" | "landscape" | "unknown" {
+function getOrientationValue(configuration: android.content.res.Configuration): "portrait" | "landscape" | "unknown" {
+    const orientation = configuration.orientation;
+
     switch (orientation) {
         case android.content.res.Configuration.ORIENTATION_LANDSCAPE:
             return "landscape";
@@ -279,6 +296,19 @@ function getOrientationValue(orientation: number): "portrait" | "landscape" | "u
     }
 }
 
+// https://developer.android.com/guide/topics/ui/look-and-feel/darktheme#configuration_changes
+function getSystemAppearanceValue(configuration: android.content.res.Configuration): "dark" | "light" {
+    const systemAppearance = configuration.uiMode & android.content.res.Configuration.UI_MODE_NIGHT_MASK;
+
+    switch (systemAppearance) {
+        case android.content.res.Configuration.UI_MODE_NIGHT_YES:
+            return "dark";
+        case android.content.res.Configuration.UI_MODE_NIGHT_NO:
+        case android.content.res.Configuration.UI_MODE_NIGHT_UNDEFINED:
+            return "light";
+    }
+}
+
 function initLifecycleCallbacks() {
     const setThemeOnLaunch = profile("setThemeOnLaunch", (activity: androidx.appcompat.app.AppCompatActivity) => {
         // Set app theme after launch screen was used during startup
@@ -380,19 +410,35 @@ function initComponentCallbacks() {
             // TODO: This is skipped for now, test carefully for OutOfMemory exceptions
         }),
 
-        onConfigurationChanged: profile("onConfigurationChanged", function (newConfig: android.content.res.Configuration) {
-            const newConfigOrientation = newConfig.orientation;
-            const newOrientation = getOrientationValue(newConfigOrientation);
+        onConfigurationChanged: profile("onConfigurationChanged", function (newConfiguration: android.content.res.Configuration) {
+            const newOrientation = getOrientationValue(newConfiguration);
 
             if (androidApp.orientation !== newOrientation) {
                 androidApp.orientation = newOrientation;
+                orientationChanged(getRootView(), newOrientation);
 
                 notify(<OrientationChangedEventData>{
                     eventName: orientationChangedEvent,
                     android: androidApp.nativeApp,
                     newValue: androidApp.orientation,
                     object: androidApp
                 });
+
+                return;
+            }
+
+            const newSystemAppearance = getSystemAppearanceValue(newConfiguration);
+
+            if (androidApp.systemAppearance !== newSystemAppearance) {
+                androidApp.systemAppearance = newSystemAppearance;
+                systemAppearanceChanged(getRootView(), newSystemAppearance);
+
+                notify(<SystemAppearanceChangedEventData>{
+                    eventName: systemAppearanceChangedEvent,
+                    android: androidApp.nativeApp,
+                    newValue: androidApp.systemAppearance,
+                    object: androidApp
+                });
             }
         })
     });

diff --git a/tns-core-modules/application/application.d.ts b/tns-core-modules/application/application.d.ts
@@ -101,6 +101,16 @@ export interface OrientationChangedEventData extends ApplicationEventData {
     newValue: "portrait" | "landscape" | "unknown";
 }
 
+/**
+ * Event data containing information for system appearance changed event.
+ */
+export interface SystemAppearanceChangedEventData extends ApplicationEventData {
+    /**
+     * New system appearance value.
+     */
+    newValue: "light" | "dark";
+}
+
 /**
  * Event data containing information about unhandled application errors.
  */
@@ -281,16 +291,29 @@ export function on(event: "uncaughtError", callback: (args: UnhandledErrorEventD
 export function on(event: "discardedError", callback: (args: DiscardedErrorEventData) => void, thisArg?: any);
 
 /**
- * This event is raised the orientation of the current device has changed.
+ * This event is raised when the orientation of the application changes.
  */
 export function on(event: "orientationChanged", callback: (args: OrientationChangedEventData) => void, thisArg?: any);
 
+/**
+ * This event is raised when the operating system appearance changes
+ * between light and dark theme (for Android);
+ * between light and dark mode (for iOS) and vice versa.
+ */
+export function on(event: "systemAppearanceChanged", callback: (args: SystemAppearanceChangedEventData) => void, thisArg?: any);
+
 /**
  * Gets the orientation of the application.
  * Available values: "portrait", "landscape", "unknown".
  */
 export function orientation(): "portrait" | "landscape" | "unknown";
 
+/**
+ * Gets the operating system appearance.
+ * Available values: "dark", "light".
+ */
+export function systemAppearance(): "dark" | "light";
+
 /**
  * This is the Android-specific application object instance.
  * Encapsulates methods and properties specific to the Android platform.
@@ -425,6 +448,12 @@ export class AndroidApplication extends Observable {
      */
     orientation: "portrait" | "landscape" | "unknown";
 
+    /**
+     * Gets the system appearance.
+     * Available values: "dark", "light".
+     */
+    systemAppearance: "dark" | "light";
+
     /**
      * The name of the application package.
      */
@@ -604,6 +633,12 @@ export interface iOSApplication {
      */
     orientation: "portrait" | "landscape" | "unknown";
 
+    /**
+     * Gets the system appearance.
+     * Available values: "dark", "light".
+     */
+    systemAppearance: "dark" | "light";
+
     /**
      * The [UIApplication](https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIApplication_Class/index.html).
      */
@@ -627,7 +662,9 @@ export interface iOSApplication {
     removeNotificationObserver(observer: any, notificationName: string): void;
 }
 
-/* tslint:disable */
+/**
+* @deprecated
+*/
 export interface RootViewControllerImpl {
     contentController: any;
 }