The 34-year-old actress is set to portray green-skinned humanoid Gamora in the comic book blockbuster, reported Contactmusic.
Gamora is the last of her race, the Badoon, and is trained to be an assassin by villain Thanos before eventually turning against him.
If Saldana signs up for the film, which is set in space, she will join Chris Pratt, who is playing Star-Lord, and former WWE wrestler Dave Bautista, who will portray Drax the Destroyer.
'Guardians of the Galaxy' will be directed by James Gunn and shooting is due to start in June.
Saldana will be next be seen in 'Star Trek Into Darkness', which hits theatres in May.