The Mavericks also get cash in the trade announced Thursday along with the right to send Houston the 2020 second-round pick they obtained from Golden State in 2016.
The 6-foot-10 Onuaku was a second-round pick by the Rockets two years ago and averaged 3.0 points and 2.3 rebounds in six career games. The Maryland native played two years at Louisville before turning pro.
Leunen goes back to the Rockets 10 years after they drafted him in the second round out of Oregon. The native of Washington state has been playing professionally in Turkey, Italy and Germany. Dallas got Leunen from the Clippers last month as part of a deal that sent forward Johnathan Motley to Los Angeles.