Overlord will begin airing on Netflix on April 14th - listed on the new and popular section of the website, it hasn't yet listed how many seasons or in what format (subtitled, dubbed). Safe to say season 1 will land, though 4 seasons are currently available on dedicated anime streaming service Crunchyroll.
Hopefully this opens the door for the movie, which is on track to release in Autumn of this year.
In the meantime, enjoy the trailer below:
Source: AnimeBluRayUK