[1] With 13 top-10 finishes out of 25 tournaments played in 2018, she was named the LPGA Rookie of the Year,[1][2] and completed the 2018 season as the 10th-ranked female player in the world.

Ko completed the 2019 season with the official money title ($2,773,894), the Vare Trophy for the lowest scoring average (69.06), and was named LPGA Player of the Year.

[3] In 2020, she won the LPGA official money title ($1,667,925) having played in only four tournaments due to the COVID-19 pandemic, and finished the season as the number one ranked player in the world.

[11] On 28 July 2019, Ko clinched her second major title of the season, firing a final round 4-under 67 in the rain to win the Evian Championship by two shots with a 15-under total of 269.

[14] Having won the season's money title and Vare Trophy for lowest scoring average, Ko was named the LPGA Rolex Player of the Year for 2019.

[20][21] In November 2021, Ko successfully defended her title at the CME Group Tour Championship in Naples, Florida.

[24][25] Ko successfully defended her HSBC Women's World Championship title in Singapore on 5 March, defeating Nelly Korda by two strokes.

[26] She reclaimed the world number one ranking on 22 May 2023, a week after winning her third Cognizant Founders Cup title, beating Minjee Lee in a playoff.

[27] Ko passed Lorena Ochoa for most weeks at number one in the Women's World Golf Rankings with 159 as of 26 June 2023.