Fiennes was born in Salisbury, Wiltshire, England. He was raised in West Cork, Ireland, along with his six brothers and sisters, including his twin, Jacob, and older brother Ralph Fiennes.
After leaving art school, Fiennes worked with the Young Vic Youth Theatre, and then went on to train at the Guildhall School of Music and Drama. His first professional stage appearance was in the West End in "The Woman in Black," followed by "A Month in the Country," opposite Helen Mirren. Fiennes, then, was a member of the Royal Shakespeare Company for two seasons.
Fiennes made his television debut as Willy in The Vacillations of Poppy Carew. His first feature film was 1996's Stealing Beauty, co-starring Liv Tyler. His biggest film, to date, was Shakespeare in Love, which won for Best Picture at the Academy Awards for 1998.
Fiennes is currently starring in his recent flick, 2003's Sinbad: Legend of the Seven Seas as the voice of Proteus.