The world number one rallied back from falling 7-4 behind with an unstoppable five-leg streak to take control before closing out the win.
van Gerwen will take on Gary Anderson in the final, which he has now reached in three consecutive seasons.
After falling behind, van Gerwen levelled by following his first 180 with a clinical 121 checkout.
The next four legs were shared before van Barneveld took out 64 keep the match on throw and lead 4-3.
van Gerwen pegged double 18 to restore parity but missed a dart at double 16 to break before seeing his opponent land the same target.
van Barneveld then fired some incredible arrows in the tenth leg, in which he narrowly missed double twelve for a nine-darter. van Gerwen missed a dart at the bull to steal the leg with a 161 finish and ‘Barney’ returned to bed the double and grab the game’s first break of throw.
The five-time World Champion took out 110 to move three-legs clear with ‘Mighty Mike’ waiting on a double to break back.
van Gerwen took out a brilliant 127 finish to reduce the deficit and followed it up with a fantastic 11-dart-leg to break and move within a leg of his compatriot.
The world number one then took out 100 to level, finishing with two double tops.
And he made it four legs in a row to move ahead for the first time in the match at 8-7.
That became five consecutive legs as he turned the contest on its head and moved with a leg of victory.
van Barneveld pulled a leg back but van Gerwen sealed the victory on double four.