Ariza played 67 games for the Houston Rockets last season. He averaged 11.7 points last season for Houston, and the 33-year-old will likely be looked upon as a veteran presence in a young Phoenix locker room.
Ariza was 0 for 12 from the field in Houston's Game 7 loss to Golden State in the Western Conference finals, missing all nine of his 3-point tries.
The deal was first reported by Yahoo! Sports.
The Associated Press contributed to this report.