Yes, Todoist has dark themes for all your devices!
Learn how to turn it on by changing your color themes.
Does Todoist offer a true black theme for (AM)OLED screens?
No. Even though a true black theme would save some battery over our current dark theme, we don’t regard the difference in power consumption significant enough (0.3% mW). Additionally, without an entire redesign, supporting a true black theme would make it harder to distinguish visual hierarchies and depth.
Will Todoist automatically switch to Dark Theme when I switch to Dark Mode on iOS or Dark Theme on Android?
Yes, on iOS there is an Auto Dark Mode setting - called Auto dark theme on Android - which will cause Todoist to switch to Dark Theme whenever you set your device to Dark Mode. Learn how to activate it on either platform in the instructions here.