In her rookie LPGA Tour season of 2019, Jeongeun struck the jackpot with a two-stroke victory in the US Women's Open, the event where she had tied for fifth on her major debut two years earlier. She also came joint sixth in the ANA Inspiration and tied ninth in the AIG Women’s Open at Woburn that same year.
By then she had become known as Jeongeun Lee6 to tell her apart from other Korean golfers with the same name. She hit the headlines again in 2021 with a 10-under-par 61 at the Evian Championship. It set the lowest round ever recorded in a major, male or female, but was matched two days later by Leona Maguire.
Five ahead with a round to play, however, Lee6 was caught by Minjee Lee, who shot 64 to come from seven back, and it was the Australian who took the title at the first extra hole.
Jeongeun collected her second professional title by winning the IOA Golf Classic in March 2026.