King set a blistering pace from the outset and rattled off the first three sets with minimum fuss.
Van Gerwen got on the board in the fourth set but struggled to score consistently, trailing 4-1 going into the break.
The match turned on its head from that point as Van Gerwen turned on the accelerator to blow King away with a remarkable change in form.
The Dutchman won five consecutive sets to send a raucous Irish crowd wild and claim the match by six sets to four.
Van Gerwen's maiden tournament victory in the PDC earns the 23-year-old a winner's cheque for £100,000.