Buechler, who helped Poway High School win three San Diego Section basketball titles from 1984-86, was waived Dec. 16 by San Antonio shortly before he discovered the navicular bone in his right wrist was fractured.
The injury will require five to seven weeks to heal.
The second-year forward out of Arizona was met at the Oakland Airport by Golden State Coach Don Nelson and signed the contract at Nelson's home.
Buechler will have his wrist examined today by Golden State doctors, watch the team work out, then return to San Diego until after the new year.
Buechler was also contacted by the NBA champion Chicago Bulls.
This is Buechler's first guaranteed contract and it comes with his third team this season.
He played last year for the New Jersey Nets and was waived earlier this season to accomodate the signing of rookie holdout Kenny Anderson. The Spurs picked Buechler off the waiver wire. He fractured his wrist right before Thanksgiving, but the initial x-ray was negative.