Hull had not won since taking the Lalla Meryem Cup in March of 2014 at age 17 in Morocco.
The final day of the 2016 campaign also saw South Korean Chun In-Gee birdie the last three holes to edge New Zealand's top-ranked Lydia Ko for the Vare Trophy for the season's low scoring average in a battle that went down to the last stroke.
Ariya, whose first five LPGA titles this year included her first major at the Women's British Open, only shared fourth but with teenager Ko only sharing 10th, the result was good enough to claim Player of the Year and Race to the Globe season points bonus.
"I had my goal to win my first tournament and I did. To win the Player of the Year, it's huge," said the Thai.
Hull, a 20-year-old from England, won her first US title and first crown since 2014 by firing a final-round 66, six-under par, to finish on 19-under 269 -- shattering the old Tiburon Golf Club mark of 271 set by American Cristie Kerr last year.
"I was pretty calm," Hull said. "When I'm on the golf course I try not to think about golf. It makes me think I'm not leading the golf tournament and that's what I did."
Hull, ranked 30th in the world, had not won since taking the Lalla Meryem Cup in March of 2014 at age 17 in Morocco on the Ladies European Tour.
Hull, who made only eight birdies last year at the Naples, Florida course, sank 23 this year, including an all-but clincher on the penultimate hole.
Level with South Korea's Soyeon Ryu after a day-long duel, Hull birdied the par-five 17th hole while Ryu made bogey and both closed with pars to end the last drama on a day of intense trophy fights.
Ryu fired a 67 to finish second on 271 while Jennifer Song birdied five of the last six holes to shoot 68 and take third on 273, one stroke ahead of fellow American Mo Martin, Spain's Beatriz Recari and Ariya.
Three days before her 21st birthday, Ariya took the Race to the Globe with 6,800 points to 5,050 for Ko despite the Kiwi's second-round 62.
"I thought she was going to win everything, that's what I thought," Ariya said of Ko, who hugged all the rivals who left her empty-handed. That included Chun, whose fight for the Vare Trophy that began in January went down to their last shots.
Ko took a bogey at the third and closed the front nine with a double bogey, then birdied three holes in a row to begin the back nine, while Chun opened with a birdie, took a double bogey at the third and answered a bogey at nine with a birdie at 13.
"I got my putter rolling on the back nine," Ko said. "I tried to fight it out to the end. In-Gee had a really great finish."
Chun and Ko each birdied the par-three 16th but when Ko made bogey at 17 and Chun birdied, Ko's lead was trimmed to one-thousandth of a stroke. Chun then curled in an eight-foot birdie putt at 18 to take the trophy.
"If knew if I make putt I have a chance for the Vare Trophy," Chun said. "I made the big putt. I was so happy."
Hull never trailed Ryu, but the Korean's five-foot birdie putt at 16 left them level. Ryu found a deep bunker at the 17th green and pitched sideways to escape while Hull just cleared the trap on her approach and sank a five-foot birdie for her victory margin.