Kemp comes from an English family. He has one brother and one sister. When Will was 9 his mother suggested that he take up dance lessons as a hobby. It soon became apparent that dancing was his talent.
When Will was 17 he auditioned for Mathew Bourne's impressive dance company, Adventures in Motion Pictures (AMP). There he was spotted by Paramount Studio head, Sherry Lansing. She was "so smitten with his performance" that she immediately dubbed him "the James Dean of Ballet."
Will's début was in the movie Van Helsing as the Werewolf.