The league was founded in 1994 by Portland businessman Bruce L. Engel. It began play in 1995, with the following teams:
In 1996, Surrey left the league, and the Reno, Nevada Chukars were added. Long Beach won its second consecutive title.
In 1997, the Palm Springs team decided to move to Oxnard, California, but sat out the year while they made their move. The team added the Chico, California Heat. Chico won the league championship in their first season in the league.
In 1998, the Salinas team disbanded, and the Oxnard team rejoined the league. The Sonoma County team won the league championship. The Grays Harbor team had suspended operations halfway through the season, and the league took over management of the team, which went on an extended 68-game road trip with no home stadium.
In 1999, the team disbanded the former Grays Harbor team, and operated six teams for the season. Tri-City won the league championship for the year.
In 2000, the league expanded to include Yuma, Arizona and Scottsdale, Arizona, which called itself the Valley Vipers. The Zion Pioneerzz won the league championship.
In its final year of 2002, the Western Baseball League operated six teams. In the Northern Division were the Chico Heat, Sonoma County Crushers, and the Yuba-Sutter Gold Sox. In the Southern Division were the Long Beach Breakers, Solano Steelheads, Yuma Bullfrogs. The Chico Heat won the league championship in the league's final season.