As a freshman at Sungkyul University, he was selected for the South Korean national bobsleigh team in early 2010 and made his first international appearance at the North American Cup in Park City in November 2010.

After a couple of rocky seasons with different pilots, Seo temporarily quit bobsleigh to focus on studying in college.

Their performances gradually deteriorated in the 2016–17 season when the duo began to use the domestic sled that was manufactured by the Hyundai Motor Company, South Korea's largest automaker.

Prior to the 2018 Winter Olympics, the duo eventually decided to use Larvia's BTC sled again that they became the World Cup overall champion with.

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.