Park, currently world No. 2 who won the Player of the Year and the Rookie of the Year honors in 2017, has now recorded multiple victories in each of the past three seasons. She had two wins as a rookie and three more in 2018.
Park, who traded two birdies with a bogey on the front nine, said she should have converted more of her opportunities early on to make it easy on herself, but she tried to take it one shot at a time.
"I told my caddie (David Jones) that we had a lot of holes left," Park said. "It helped me a great deal to get into that patient mindset. I think I played really well for all three days."
When the new rankings are unveiled Monday in the United States, Park will dethrone countrywoman Ko Jin-young as the new No. 1.
Park had been at the top of the rankings in three different stretches. She first became No. 1 in November 2017 and stayed there for one week. She returned to the top spot in August 2018 and spent two months there. Most recently, Park was No. 1 again from March to April this year.
Ko has been No. 1 over the past dozen weeks. Ko was one of seven golfers sitting at 11-under through two rounds in Arkansas, two behind co-leaders Park and Carlota Ciganda, but Ko managed only a 70 in the final round with two birdies and a bogey.
Park said she felt a lot of pressure whenever she was No. 1 and she's promised herself not to get caught up in her ranking positions.
"Whether I am No. 1 in the rankings or not, I'll continue to play the same way," Park said. "When I came down from No. 1 (in April), I was determined not to put pressure on myself if I returned to the top. It's always great to be back on top."
The world rankings evaluate a player's performance over a rolling two-year period, with an extra emphasis on their results over the most recent 13 weeks.
In 11 tournaments this season, Park has two victories and two runner-up finishes.
This was the 17th tournament of this LPGA season, and six South Korean players have combined for eight wins.
Park shared the overnight lead with Cigana at 13-under, and seven golfers, including Park In-bee and Kim Hyo-joo, were trailing by two shots.
Park In-bee finished first among those three South Koreans at 17-under after a bogey-free round of 65. Kim followed suit moments later with her round of 65, though she found a greenside bunker with her second shot at the par-5 18th to cost herself a potential birdie.
Park Sung-hyun stood on the 18th tee at 17-under. She reached the 18th green in two, and rolled her first putt to just inches from the cup and set up an easy clinching putt. (Yonhap)