Evans, who got into the competition as a replacement for injured New York guard Iman Shumpert, earned 29 percent of 3 million text message votes cast by fans.
This was the first year that fans had total control of voting, a major tweak from past competitions.
Evans earned the win over Houston's Chase Budinger, Indiana's Paul George and Minnesota's Derrick Williams.
Evans dunked with a camera on his head, dunked two basketballs while jumping over a seated assistant and then donned a Karl Malone jersey while dunking over mailman-dressed comedian Kevin Hart.
This year's contest lasted three rounds, but the four participants had only two minutes per round to complete a single dunk.