[2][3] He is the first South Korean player in 24 years to have won two gold medals in a single edition of the BWF World Championships, by winning the mixed and men's doubles event at the 2023 BWF World Championships, partnering with Chae Yoo-jung and Kang Min-hyuk respectively.

The duo immediately caught attention by winning the Korea Open, defeating higher-ranked pairs such as Satwiksairaj Rankireddy and Chirag Shetty, Mohammad Ahsan and Hendra Setiawan, and their final opponent Fajar Alfian and Muhammad Rian Ardianto in the journey.

[12] Seo resumed playing mixed doubles with Chae Yoo-jung at the Indonesia Masters as semi-finalists.

[18] Seo continuing his good form in the next tournament by being a runner-up in India Open[19] and winning Thailand Masters[20] with another partner, Jin Yong.

In March, Seo paired with Kim again and won German Open against France's Popov brothers (Toma Junior and Christo).