Seo along with pilot Won placed sixth out of 30 teams in the two-man event at the 2018 Winter Olympics in Pyeongchang on February 19, recording an overall time of 3:17.40 in four runs. Although they failed to win a medal, it was the best Olympic result by an Asian bobsleigh team. The following week, on February 25, the South Korean four-man team of Seo, Won, Kim Dong-hyun and Jun Jung-lin won a surprising silver medal in the four-man event, tying with a German team led by Nico Walther. With the silver medal, South Korea became the first Asian nation to claim an Olympic medal in a bobsleigh event.