The Kings will receive center Alex Oriakhi and a $7 million trade exception in the deal, sources said.
Thomas, 25, had run his course with the Kings. They didn't want to make him a starter and he didn't want to stay. The Suns see Thomas as the third guard with starters Eric Bledsoe and Goran Dragic, an intriuging trio in coach Jeff Hornacek's system.
The Kings took Thomas with the 60th overall pick of the 2011 NBA draft. He averaged 20.3 points and 6.3 assists last season.