His professional umpiring career began after he attended the Joe Brinkman Umpire School in 1989, and he worked his way up to the Pacific Coast League for the 1993 season. He made his major league debut in 1994. For the next five seasons, Barrett served as a fill-in umpire for vacationing or injured major league umpires. Barrett was one of the 25 umpires promoted in the wake of the Major League Umpires Association's mass-resignation strategy in July 1999. His five years of experience made him one of the most experienced of the 25 umpires called up to fill the sudden vacancies.