The 1989 Big Sky Conference Men's Basketball Tournament was held March 9–11 at the BSU Pavilion at Boise State University in Boise, Idaho. Regular season co-champions Idaho and Boise State, defending tournament champions and host, met in the championship game. Both had 13–3 conference records with five overall losses, and had split their season series with home wins. Under first-year head coach Kermit Davis, Idaho prevailed, 59–52. It was the Vandals' third Big Sky tournament title; the wins in 1981 and 1982 were under head coach Don Monson.