Iman Shumpert is a champion once again ... and just like coming back from a 3-1 lead, it was a shocking upset win.
The former Cavs guard -- who made history when he became the first former pro hoops player to advance to the finals of "DWTS" last week -- took home the Mirror Ball trophy with his partner Daniella after a freestyle dance that had all of social media talking.
It was a nail-biter 'til the end ... and a lot of folks thought Siwa was going to take it all.