The Doctor Who star has boarded the cast of the blockbuster sequel in a major role that will expand in the second and third installments of the new trilogy.
According to Deadline, Smith is "the final major piece" of casting for the project, which is being directed by Thor: The Dark World's Alan Taylor.
Arnold Schwarzenegger will reprise his role as the cyborg T-800 in a plot that will reportedly intersect directly with James Cameron's 1984 original.
In a recent posting on HitFix, it's been claimed that the new Terminator script - from Laeta Kalogridis and Patrick Lussier - will see scenes reprised from the 1984 original, similar to how Back to the Future II replayed key sequences from its predecessor.
Terminator: Genesis's cast also features Game of Thrones star Emilia Clarke as Sarah Connor, Jason Clarke as John Connor, Jai Courtney as Kyle Reese and Dayo Okeniyi as Danny Dyson.
The blockbuster has already started production for release in cinemas in summer 2015.