The 2025 Big West Conference baseball tournament determined the conference champion for the Big West Conference at the end of the 2025 college baseball season. The top five teams met at Cal State Fullerton's on campus venue, Goodwin Field from May 21 through 24. This was the first Big West Conference postseason championship event since the 1998 season, ending a 27-year hiatus. The Cal Poly Mustangs won the championship, defeating UC Irvine in back-to-back elimination games, receiving the conference's automatic bid. UC Irvine also received an at-large bid. Both teams went 2-2 in the tournament, losing in their respective regional final.
The top five finishers from the regular season were seeded one through five based on conference winning percentage. Seeds No. 1, No. 2, and No. 3 received a bye into the double elimination bracket, while No. 4 and No. 5 battled in a single elimination the first round.
The following players were members of the Big West Conference All-Tournament Team.