C.J. Sapong also scored for Kansas City, which will play host to either Portland or Real Salt Lake on Dec. 7. Sporting and the Dynamo played to a scoreless draw two weeks ago in the first leg of the conference final.
Houston, the runner-up in 2011 and 2012, will miss the title game for the first time in three years.
The Dynamo went up 1-0 in the 3rd minute on a goal from Oscar Boniek Garcia, whose shot deflected off center back Matt Besler after a headed pass from Brad Davis.
Sapong responded in the 14th minute, scoring from short range after Houston defender Bobby Boswell misplayed Graham Zusi's through ball.
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