The Warriors announced Barron's signing before they played at the Charlotte Bobcats on Saturday night.
Barron appeared in 21 games last season with Portland, Phoenix and Milwaukee. He averaged 3.8 points and 3.6 rebounds in 14.6 minutes per game and also made seven starts.
The 7-footer is expected to fill the backup role behind starter Andris Biedrins after Brown was injured in Golden State's 111-106 overtime victory over Miami on Tuesday night. Brown is having surgery on his pectoralis major, the large chest muscle that attaches to his right shoulder, and is expected to miss at least three months.