Collette has won four Australian Film Institute awards, including the Australian Best Actress in a Lead Role for Muriel's Wedding in 1994, a role for which she gained 18kg (40lb) in seven weeks. In 1996, she was part of the ensemble cast of the comedy, Cosi. She received an Academy Award nomination for her role as the mother of a troubled boy in the U.S. film The Sixth Sense, which also starred Bruce Willis and Haley Joel Osment.

She has also received broad acclaim on Broadway, starring as Queenie in Michael John LaChiusa's musical work, The Wild Party. For this role, Collette received a Tony Award nomination for Best Performance by a Leading Actress in a Musical.

Collette had to turn down the title role in Bridget Jones's Diary because she was committed to perform on Broadway at the time. She then auditioned for the role of ambitious murderess Roxie Hart in the hit film Chicago; She almost got the part but, because she wasn't a well known enough actress, she lost the ro