West agreed to a one-year deal worth the veteran's minimum salary of $1.55 million, according to various reports.
West, who turns 36 in August, opted out of a $12.6 million salary one summer ago to play for San Antonio at the veteran's minimum. He recently opted out of his option with the Spurs to become a free agent and has accepted a second straight low-priced deal.
The Warriors are shopping for bargain-basement players after winning the derby to add All-Star forward Kevin Durant to a team that includes guards Stephen Curry and Klay Thompson and forwards Draymond Green and Andre Iguodala.
Golden State also has reached a deal with former Dallas Mavericks center Zaza Pachulia.
West averaged 7.1 points in 78 games for San Antonio. The 13-year veteran has career averages of 14.8 points and 6.9 rebounds.
West played his first eight seasons for New Orleans and spent four years with the Pacers before leaving to join San Antonio.