He was runner-up at the 2017 Duke of York Young Champions Trophy in England and the 2019 Australian Master of the Amateurs.

In 2018, he was runner-up at the Asia-Pacific Amateur Championship, before winning the event in 2021 in a playoff with Hong Kong's Taichi Kho.

[6] In 2021, he was runner-up at the Token Homemate Cup, a stroke behind Takumi Kanaya, and won the Panasonic Open in a playoff.

After he made the cut at the 2022 Sony Open in Hawaii, he rose to 188th in the Official World Golf Rankings.

[10] In March 2024, Nakajima claimed his first victory on the European Tour, winning the Hero Indian Open wire-to-wire by four shots.