The Yorkshire county player did it in style, carding seven birdies in his final 11 holes as he shot rounds of 71 68 at Pannal to finish on five-under 139.
Wheatley's Kealan Lowe placed second after two rounds of 70, and he in turn was one ahead of Shipley's Daniel Rowley (71 70).
Chris Atkins (Ilkley; 74 68) edged fourth place from another Yorkshire county player, Hornsea's Luke Robinson (73 69), by virtue of a better second round.
Hague, whose previous Order of Merit victories came in the 2014 Sand Moor Masters and the 2015 Fulford Mackenzie Salver, made the most of Pannal having three reachable par-5s on its back nine.
He was out in 37 in both rounds, but came home in 34 shots in round one and trimmed that total to 31 for his afternoon 68.
Hague, Lowe and Tom Broxup (Cookridge Hall) were all on four under for the tournament stood on the 17th tee in the second round.
The Malton & Norton man made a crucial birdie at the hole and a steady par at the last to claim victory.
Anthony Harwood (Blackburn) won the prize for the best morning round, 70, and Otley's George Muscroft took the afternoon honours with 69.