GAUTIER Antoine

After installing the plugin. 
You’ll have a new menu in your admin page “GAPlugin”. 
It will have a “darkmode” menu. 
Here you’ll be able to activate a test affecting the body of your website.
You’ll be able to modify your CSS (Cascade Style Sheet) to manage your darktheme: 
– for the light theme :root 
– for the dark theme [data-theme=”dark”] 
You can take a look in the test mode to see how to use it.
You just have to use the shortcode in your theme to display the checkbox for the darkmode. 
Here is the shortcode to use: [GAP-darkmode]
Enjoy ! 
Take a look at my website <a href="https://gautierantoine.com" rel="nofollow ugc">GautierAntoine.com</a>

gaplugin-darkmode

Use a shortcode to create a light/dark mode.

Nicolas Notararigo

It’s not a simple plugin, it’s a complete style of Admin Panel in Dark Mode. 
This plugin transform your WP Admin in DarkMode. Install just plugin and activate it to see dark mode !

DarkPress

I like the concept (very nice if you manage different WP installations, you know where you are at a glimpse with admin schemes) and it’s efficient. But not perfect for the moment (I dont like the effect of pink buttons).

Dark site of Admin

It's a simple plugin to modify your WordPress admin interface in DarkMode

gaplugin-darkmode vs DarkPress