The Sherlock star revealed to The Sunday Times Magazine that he will play MI6 agent Peter Guillam in the remake from Let The Right One In director Tomas Alfredson.
Tinker, Taylor is based on John le Carré's spy novel and was previously adapted for a 1979 TV series with Michael Jayston in the Guillam role and Sir Alec Guinness as his mentor George Smiley.
Gary Oldman is expected to play Smiley in the new version, while Michael Fassbender, Colin Firth and David Thewlis have all held talks about starring in the movie.
Cumberbatch, who counts Atonement and Four Lions among his big screen credits, is also due to star in Steven Spielberg's upcoming War Horse.
Discussing the differences between his two forthcoming film roles, Cumberbatch said: "War Horse is a thrill, and an incredible CV filler, and Spielberg is amazing... but to me [Tinker, Tailor, Soldier, Spy] is... such a grown-up role."