LaBute is of French Canadian, English and Irish ancestry, and was raised in Spokane, Washington. He studied theater at Brigham Young University (BYU), where he joined The Church of Jesus Christ of Latter-day Saints. At BYU he also met actor Aaron Eckhart, who would later play leading roles in several of his films. He produced a number of plays that pushed the envelope of what was acceptable at the conservative religious university, some of which were shut down after their premieres. However, he also was honored as one of the "most promising undergraduate playwrights" at the BYU theater department's annual awards. LaBute also did graduate work at the University of Kansas, New York University, and the Royal Academy of London.
LaBute's first produced play, Filthy Talk for Troubled Times (1989)--a series of biting exchanges by two 'everymen' in a bar—was staged from June 3–5, 2010 by MCC Theater in Manhattan as a benefit for MCC's Playwrights' Coalition and their commitment to developing new work. LaBute also directed the reading.