He made his debut in 1986, after directing some short-films and writing for influential film magazine Cahiers du cinema. Other big name directors such as Francois Truffaut and Jean-Luc Godard also started as writers for the same magazine.
Assaya's father was French director/screenwriter Jacques Remy (1910-1981). He started his career in the industry by helping him. He ghostwrited episodes for TV shows his father was working on when his health failed.
His biggest hit to date has been Irma Vep, starring Hong Kong star Maggie Cheung, that manages to be both a tribute to French director Louis Feuillade and to Hong Kong cinema.
While working at Cahiers du cinema, Assayas wrote lovingly about European film directors he admires but also about Asian directors. One of his latest films is a documentary about Taiwanese filmmaker Hou Hsiao-hsien.
He married Maggie Cheung in 1998. They divorced in 2001.