Thomas produced 31 points, his second largest total of the season. Seven of his 10 field goals came from 3-point range.
It was the seventh road victory of the campaign for the Kings. Only Charlotte, with six, has fewer in all of the NBA.
Golden State was led by David Lee with 20 points.
Although the Warriors hold down the sixth spot in the Western Conference playoff chase, they still have work to do to clinch a post-season berth. Utah, which is in the ninth position, moved within 4 1/2 games of the Warriors with a win Wednesday.