The announcement Thursday will keep Thompson with the Warriors through the 2013-14 season.
The 22-year-old played in all 66 games last season. He averaged 12.5 points, 2.4 rebounds, 2.0 assists and 24 minutes to earn first-team All-Rookie honors.
Golden State drafted Thompson 11th overall out of Washington State. He led all rookies in 3-point percentage at 41 percent, and 3-pointers made with 111.
The Warriors open the regular season Wednesday night at Phoenix. Thompson is expected to start at shooting guard this season.