With a string of near-misses at the majors and Olympic champion Park In-bee breathing down her neck, it was a relieved Sei Young Kim who tapped in the winning putt to claim the Women's PGA Championship on Sunday.

Kim's triumph at Aronimink Golf Course after a scintillating final round 63 put paid to her status as the most prolific winner on the LPGA Tour among active players never to have won a major title.

"I'm so excited. I'm really hiding my tears at the moment. It was amazing that I really won it. So I'm very happy and excited that I got it done," the 27-year-old South Korean said, beaming next to the winner's trophy.

Seven-times major champion Park had beaten Kim for the 2015 title at Westchester Country Club and was only three strokes behind her compatriot going into the final round.

A five-under round might get the job done, she thought.

Park duly delivered with a 65 but it was not enough as overnight leader Kim rose to the challenge with her seven-under-par 63 that saw her finish on a 14-under total of 266, five ahead of Park.

"Obviously Sei-young was just much better than anyone else out there today," said Park, who had been chasing a fourth win in the event.

"It was just so hard to believe that she never won a major before because it felt like she won a few," she said of Kim, who has claimed at least one Tour win each season since 2015.

Kim, who was in a tie for second at the 2018 Evian Championship, one of the five women's majors, admitted to struggling with nerves before teeing off on Sunday and kept her eyes averted from the leaderboard during her round.

"I won't lie, I did feel the pressure starting last night," she said. "I actually arrived about 30 minutes later than I normally do at the golf course.

"I did not look at the scoreboard once. I knew In-bee was going to play great. But I had to just focus on playing my own game, one shot at a time."

Nasa Hataoka and Carlota Ciganda tied for third at seven-under. Anna Nordqvist (four-under) and Brooke Henderson (three-under) both played in Kim's group and finished fifth and sixth.

Perth's Hannah Green, Australia's top finisher, tied for 23rd after an impressive final round of 67

Kim is the latest addition to a growing list of first-time major winners in recent years, a sign of growing parity.

Her victory means nine of the last 10 major champions had never won one before.

She joins Sophia Popov (Women's British Open) and Mirim Lee (ANA Inspiration) as this year's major champions.

As she approached 18, the trophy sitting out near the hole for her to see, pretty much everyone out at Aronimink lined the ropes.

She got a big ovation after her tap-in sealed the win.