In 2016, Olesen won the International Juniors of Belgium and was runner-up at the English Boys' Open Amateur Stroke Play Championship for the
Carris Trophy, where he shot a final round of 62 and lost a playoff to Angus Flanagan. He was bronze medalist at various Danish National Championships for four-straight years, between 2017 and 2020, before winning the Danish National Match Play Championship in 2022. He plays
left-handed. Olesen has represented the Danish National Team, including at the 2017
Junior Golf World Cup in Japan and the
2023 Eisenhower Trophy in
Abu Dhabi. His team finished runner-up at the
2023 European Amateur Team Championship, losing to Spain in the final, where Olesen beat
José Luis Ballester, 4 and 3. Olesen attended
Ranger College in 2019–20 where he won the Texas Intercollegiate Tournament in his collegiate debut. He finished the season with a scoring average of 69.53 as the top-ranked junior college player according to GolfStat, and received the NJCAA Phil Mickelson Outstanding Freshman Award. He then spent three seasons at
Texas Christian University between 2020 and 2023 where he was a co-medalist at The Prestige and named to the
Big 12 All-Tournament team. He spent the 2023–24 season as a graduate student at the
University of Arkansas, where he earned All-America honors and played in the
Arnold Palmer Cup. In July 2024, Olesen made history by becoming the first Dane to win
The Amateur Championship, triumphing, 4 and 3, against
Dominic Clemons in the 36-hole final at
Ballyliffin Golf Club in Ireland. The victory earned him a spot in the
2024 Open Championship at
Royal Troon, where he made the cut to finish tied 60th alongside
Phil Mickelson and defending champion
Brian Harman. ==Professional career==