The final installment of Peter Jackson's fantasy trilogy also won the prizes for best director, best composer Howard Shore and best ensemble cast, which included Sean Astin, Orlando Bloom, Ian McKellen, Viggo Mortensen, Andy Serkis, Liv Tyler and Elijah Wood.
Clint Eastwood's crime drama "Mystic River" earned two awards: one for Sean Penn for best actor and the second for Tim Robbins for best supporting actor. Eastwood was also honored with a lifetime achievement award.
Charlize Theron took home the best actress trophy for her portrayal of a serial killer in the searing drama "Monster," while Renee Zellweger won the award for best supporting actress for her role as a plucky southern farm girl in "Cold Mountain."
The Critics' Choice Awards ceremony was organized by the Broadcast Film Critics Association and held Saturday night at the Beverly Hills Hotel.