The PGA Tour rookie birdied three of his final four holes, including a length birdie putt at the last, to close with a 3-under 67 and finish four shots clear of J.J. Spaun in the final event of the year.
It's the second year in a row that a rookie has won at the windy Sea Island Club's Seaside Course, with Cook following in the footsteps of Mackenzie Hughes last year.
"It was definitely exciting -- real brutal with the wind," Cook said. "I got off to a slow start, but I was able to keep my head level and know there was a lot of golf to be played. With the wind and those conditions, a lot could happen."
Cook, who had held the overnight lead, saw his advantage over the field shrink after Spaun twice reduced his lead to a single shot - most poignantly on the 16th hole. However, a missed birdie on the 15th and dropped shot on the 17th put Cook back in the driving seat, and with the 26-year-old making birdies on 15, 17 and 18, it turned out to be a far more straightfoward victory than it looked like it might be.
"That [Spaun's miss at No. 15] was big," said Cook, who said he's an obsessive leaderboard-watcher and knew exactly when Spaun had come within a shot.
Brian Gay, who was the oldest contender of the week at 45 years old, eagled the par-4 18th hole from 161 yards with a 9-iron to break out of a five-way tie for third and finish at 16 under with a final-round 68.
Cook, who has Gay's former caddie, Kip Henley, carrying his bag, never slipped after a bogey at the second hole, just his second of the week. He missed only two fairways in the final round and made par after four of his five missed greens. He led the field in scrambling, converting 11 of 12 pars after missing greens, and tied for fourth by hitting 48 of 56 fairways.
"With Kip on the bag, he was able to keep me in the moment and keep me pressing instead of playing conservative. There was a lot of stuff going on, mostly up here," Cook said, tapping his head. "My ball-striking was great and, for the most part, my putting was great. Holding the nerves down, playing a good round in these conditions. ... I'm so happy."