King, who previously starred on HBO's The Leftovers which was co-created by Lindelof and Tom Perrotta based on Perrotta's novel of the same name, will be taking on the lead role.
Lindelof, who is developing the series, is executive producing with Nicole Kassell who will be directing the pilot, and Tom Spezialy.
The pilot is HBO's second attempt at developing a show based on the DC Comics property that features characters such as Doctor Manhattan, Nite Owl, Silk Spectre and Rorschach investigating the murder of one of their own before uncovering a dark conspiracy.
Lindelof is a fan of the 1986 Watchmen comic book by Alan Moore and artist Dave Gibbons. He recently announced on Tuesday on Instagram that his Watchmen series will not be a re-telling of the story and will feature new characters set in the same world.
Watchmen was previously adapted into a feature film by director Zack Snyder in 2009.