The couple have been living in London since December 2004, the Daily Mail said.
"Gillian Anderson and her husband Julian Ozanne are saddened to announce that their marriage is at an end and they are in the process of separating," said a statement released by their attorney. "At this difficult time they request that their privacy is respected. There will be no further comment."
Anderson, 37, is a native of Chicago and recently received a Bafta nod for her role of Lady Deadlock on the BBC's "Bleak House." She is best known on home soil, however, for her role as Agent Scully on Fox TV's "X Files."