Forlani was born in Twickenham (in the London Borough of Richmond upon Thames), Middlesex, South West London to Pier Forlani (an Italian) and Barbara (who was English). At the age of eleven, Forlani entered the Arts Educational School in London, where she began to study acting. During her six years at the school, she also studied dance, which led to performances on stage in The Nutcracker and Orpheus in the Underworld.

Forlani's parents moved to San Francisco in 1993, in order to allow for wider casting opportunities in Hollywood films. Subsequently, Forlani was cast in the television mini-series J.F.K.: Reckless Youth and the film Police Academy: Mission to Moscow.

In 1996, Forlani appeared in a supporting role in the blockbuster action movie The Rock. She continued to appear in both widely released and smaller-budget films. Forlani was cast in the 1998 film, Deep Rising, but due to creative conflicts left the set during the first few days of filming; that same year, her starring role in Meet Joe Black (co-starring Brad Pitt) was Forlani's most financially successful film. Next, she appeared in Antitrust, a thriller that was released in January of 2001 to mixed reviews.

Forlani was the new face of L'Oreal in 2001. She has been ranked Ranked #51 (2000) and #89 (2001) in Stuff magazine's 100 Sexiest Women, #85 (2001) in FHM magazine's 100 Sexiest Women and was slotted in Loaded's Hot 100 Babes. She is scheduled to appear for the 3rd season of CSI: NY.