The deal gives the Rockets -- a hard-capped team -- the freedom to use their midlevel exception in free agency.
The Rockets are purchasing Detroit's 2021 second-round pick -- via the Lakers -- for $4.6 million, sources told ESPN.
Ariza, 35, arrived with the Blazers in February as part of a trade with Sacramento and started every one of his 21 games for Portland, averaging 11 points, 4.8 rebounds and one steal. He shot 49% from the floor, including 40% on 3-pointers. For his career, Ariza has averaged 10.5 points, 4.8 rebounds and 2.2 assists in 16 seasons.