The 26-year-old's stunning display in Incheon started with a birdie on the par-four 10th before she repeated the feat a remarkable eight more times to become the first woman in LPGA history to close a round with nine straight birdies.
Beth Daniel had recorded nine consecutive birdies in the middle of a round in 1999 but Yang is the first to do so on either a front or back nine stretch.
Her nine-hole mark for relation to par at nine-under is also a record and her score of 27 matches the lowest total for a half round.
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"I made a couple of birdies to start the day but after a bogey (at the sixth), I figured this would be just another ordinary day," Yang told reporters.
"Then I started hitting the ball much better on the back nine and making every putt. I don't think there was any one particular turning point. I just kept on hitting the ball and making putts. This is absolutely incredible."
Yang, twice a winner on the LPGA Tour, looked to have blown her chance of creating history when a wayward chip left her 15 feet past the hole on the par-five 18th but she was soon staring at the heavens in disbelief after her final putt found the cup.
The Korean admitted she was not really conscious of her streak until playing partner Jessica Korda reminded her at the 17th hole.
"She said, 'You should go for another birdie and finish with nine straight,'" Yang said.
"And I was really nervous about that last birdie putt at the 18th. It wasn't for the championship but it just felt like it. I never thought about making history but it's an honour to be in the record books."
(Writing by John O'Brien in Singapore; Editing by Sudipto Ganguly)
