The film is a co-production between Warner Bros. and Paramount, and representatives for the latter studio, Nolan and Chalamet did not respond to multiple requests for comment.
Story follows a heroic group of explorers who travel through a wormhole and into another dimension.
Though it remains unclear whether Chalamet's deal has closed, the details of his role are being kept in a Batcave somewhere, as Nolan is famously secretive.
Jonah Nolan wrote the original script, which has since been merged with one of his brother's original sci-fi ideas. The director is also producing with Emma Thomas and Lynda Obst, while Jordan Goldberg will exec produce with Caltech physicist Kip Thorne, who serves as a technical consultant on the project.
Chalamet is an up-and-coming actor best known for playing the Vice President's son, Finn Walden, on Showtime's Emmy-winning series "Homeland." He has had a recurring role on the USA series "Royal Pains," and also played Mira Sorvino's son in Craig Gillespie's recent pilot "Trooper." He's repped by WME and attorney Lev Ginsburg.