The coming-of-age drama shot over a 12-year period also won honors for director Linklater, supporting actress Patricia Arquette and best young actor/actress for Ellar Coltrane.
"Boyhood," considered the front-runner for Oscar gold, won the Golden Globe for best dramatic film Sunday night and received six Oscar nominations Thursday morning, including for film, director, supporting actress and actor.
The dark comedy "Birdman" earned the most awards Thursday night with seven, including lead actor and comedy actor for Michael Keaton, acting ensemble, original screenplay and score. "Birdman" earned nine Oscar nominations.
"The Grand Budapest Hotel," which received nine Oscar nominations, won best comedy, as well as costume design and art direction. And "Gone Girl" received the award for adapted screenplay.
Bradley Cooper, who earned a best actor Oscar nomination for "American Sniper," won for lead actor in an action movie for his performance.
After being snubbed Thursday morning for an animated feature Oscar nomination, "The Lego Movie" won the Critics' Choice honor in that category.
Kevin Costner, Ron Howard and Jessica Chastain were the recipients of special awards. Costner took home the Lifetime Achievement Award; Howard received the LOUIS XIII Critics' Choice Genius Award and Chastain receive the group's first MVP Award.
The 20th Critics' Choice Movie Awards were presented at the Hollywood Palladium and telecast on A&E. Michael Strahan was the host.
The Broadcast Film Critics Assn. includes more than 250 television, radio and online critics in the U.S. and Canada.