Right-click on the Start menu and select the Run command. Type the
and press Enter to open the Registry Editor:
Next, navigate to HKEY_CURRENT_USER > SOFTWARE > Microsoft > Windows > CurrentVersion > Themes > Personalize. Click on Edit, followed by New and DWORD (32-Bit) Value. Rename the new key as AppsUseLightTheme:
Leave the value of AppsUseLightTheme to 0 to enable the dark theme:
Close the Registry and restart your PC to apply your new settings.
Here's a preview of how the Windows 10 dark theme:
Restore the Default Theme
If you'd like to restore Windows 10's default theme, go back to the Registry Editor and set the value of AppsUseLightTheme to 1. The changes will be applied at your next reboot.