[1] Koivun was born on May 23, 2005, in San Jose, California and grew up in Chapel Hill, North Carolina.

He won the SEC Championship by six shots and only finished outside the top-six once in 13 starts, and had the lowest adjusted scoring average (67.3) in the NCAA.

[8][9] He finished in a tie for second at the 2024 NCAA Division I Men's Individual Championship, and led the Auburn team to win the national title, the first in program history.

[1] Koivun made his PGA Tour debut in the 2024 Memorial Tournament at Muirfield Village, having earned a spot through winning the Jack Nicklaus Award.

[8] Following his freshman season with Auburn University, Koivun was the third-ranked player in the World Amateur Golf Ranking, behind Gordon Sargent, and Christo Lamprecht.