McGee's return to the Octagon had been delayed twice by injuries and he finally returned after an 11 month layoff.
His opponent, Dongi Yang, entered the bout having won his last nine fights via technical knockout.
It wasn't a barnburner in the first two rounds, but McGee and Yang finally stepped it up in the final frame, going to war and blasting each other with big punches.
Yang threatened to score his 10th straight knockout after blasting McGee with a big fight hand early in the third but he couldn't keep up with "The Crusher's" relentless pace.
McGee responded to being hurt by turning up the aggression and bloodying Yang's face up with a big series of punches and superior work on the ground.
In the end, he was awarded a unanimous decision with scores of 30-27, 29-28 and 30-28.
It looks like McGee's biggest weapon is that cardio.