Confirmed by Variety, the casting comes as rumors swirled that the actor would be joining the sci-fi thriller alongside Michael Fassbender, Noomi Repace and Guy Pearce reprising their roles from Prometheus with newcomers Katherine Waterston, Demian Bichir, Billy Crudup, and Danny McBride.
On Monday, Franco was coy and laughed when he was asked about starring in the film during an interview with Hey U Guys while promoting his latest comedy, Why Him?.
"The news is out I guess," the 38-year-old said when confronted about Alien: Covenant.
According to fan site AVPGalaxy, Franco will be having a small role as Branson, the captain of the Covenant ship which comes across a strange new planet inhabited solely by Fassbender's character, the synthetic David.
Alien: Covenant is set to arrive in theaters Aug. 4, 2017 and will be a "hard R" according to Scott.