In 1996, Mortimer made her silver screen debut playing Val Kilmer's wife in The Ghost and the Darkness, and she gained international exposure in 1998 with her performance in the historical drama Elizabeth. Mortimer then demonstrated her versatility with turns in Notting Hill (1999) and the miniseries "Noah's Ark," followed by the slasher-fest Scream 3 (2000).
Subsequent films of note for Mortimer include The Kid (2000, with Bruce Willis), Bright Young Things (2003), Match Point (2005) and the 2006 remake of The Pink Panther.