The victory helped Seattle (4-4) finish up the exhibition season with three straight victories.
Ike Diogu scored 25 points and Monta Ellis added 20 for the Warriors, who finished the preseason 6-1. Golden State rested Baron Davis and Mike Dunleavy, suiting up just nine players.
Damien Wilkins scored 18 points for Seattle. Johan Petro added 16, and Rashard Lewis had 15 in the game played at the Spokane Arena.
Seattle led by small margins most of the game, including 39-35 at the half. The score was tied 86-86 after three quarters and 98-98 at the end of regulation.
Petro's hook shot snapped a 107-107 tie with a minute left in overtime.
A team spokesperson said Jason Richardson, the Warriors' leading scorer last season with 23.2 points per game, might be ready for the season opener next Wednesday against the Lakers. Richardson did not play in any exhibition games while recovering from knee surgery.
Seattle coach Bob Hill said he expects starting center Robert Swift to miss the season opener Wednesday against Portland, but declined to speculate further on the extent of Swift's knee injury. Swift was injured in Wednesday's win over Sacramento.