A
winger who had explosive pace, Seo was nicknamed the "Nalssaendori", which means an agile man in Korean. He played for
South Korean under-23 team in the
1992 Summer Olympics in
Barcelona, and scored against
Sweden. He was reportedly offered a contract from
FC Barcelona and other European club giants after his performances in the Olympics, but he stayed South Korea to serve a two-year
mandatory military service. He also played for South Korea in the
1994 FIFA World Cup, and scored the equaliser in a 2–2 draw with
Spain. After serving in
Sangmu FC, Seo longed to play in Europe and left for
Germany and the
Netherlands to participate in tryouts. In the summer of 1997, he succeeded to contract with Portuguese club
Benfica and played four pre-season games for them. However, the
Korea Football Association didn't approve of his overseas employment to
qualify for the
1998 FIFA World Cup with him. In January 1998, Seo joined French club
Strasbourg, becoming the first South Korean, and fourth Asian to play in the
Ligue 1. He successfully spent his first season by contributing to their survival in the Ligue 1, but he was pushed to the bench the next season after his manager was replaced. In summer, he participated in the
1998 FIFA World Cup, although he got
chickenpox transferred from his son. He showed unnoticeable performance during South Korea's elimination in the group stage. In February 1999, he returned to South Korea and joined
Suwon Samsung Bluewings. He led Suwon to 12 trophies including two
Asian Club Championships for six years. Lastly, he played for
Austria Salzburg and
SV Ried in Austria. While playing in
Austrian Bundesliga, he was evaluated as the best footballer in Austria by two media
Kurier and ''''. == Managerial career ==