The two teams agreed to the deal last week, but it could not be completed until Wednesday under NBA rules.
Portland traded the rights to Kostas Papnikolaou and Marko Todorovic, and two future second-round picks, to the Rockets in exchange for Robinson.
Robinson was the fifth overall pick in last year's draft by the Sacramento Kings, but he was dealt to Houston in a February trade. He played in 70 total games last season, averaging 4.5 points, 2.8 rebounds and 15.1 minutes.
Copyright 2013 by The Associated Press
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