From a career high of 12, McGill had even been in danger of relegation from the tour, but he is already guaranteed a return to the top 50.
When Higgins took the fifth frame with a break of 111, the former world champion looked to be in the groove.
However, McGill proved the steadier of the two and a 104 break in the eighth a 93 break in the ninth secured victory.
Higgins, who turned 50 in May, was looking to become the oldest winner of a ranking title but lamented missed chances.
“Anthony hit the ball superbly well, like the way we all know he can,” he said. “A big turning point was the fourth frame when I missed an unforgivable red with the rest with the balls at my mercy.
“Then, in the last frame, I butchered a red to the middle. But every credit to Anthony, he finished the match off very well.”
