The actress is the latest star to join the ensemble cast.
Deadline was first to report the news. ET has reached out to Sony for comment.
Bullock's casting in Bullet Train comes about two months after ET learned that Bad Bunny had joined the ensemble cast, which also includes Logan Lerman, Joey King, Aaron Taylor Johnson, Brian Tyree Henry, Zazie Beetz, Michael Shannon and Andrew Koji.
David Leitch is set to direct the project. The script -- based on the Japanese novel Maria Beetle by Kotaro Isaka -- was written by Zak Olkewicz.
Details of Bullock's role have yet to be revealed, but this would mark her first film with Pitt. The two have yet to cross paths on screen, despite starring in the same franchise. Bullock played Debbie Ocean in 2018's Ocean’s 8, a spinoff of the Ocean's series in which Pitt starred alongside George Clooney, Matt Damon and more.
See more on Bullock in the video below.