Yu Nam-sung (Korean: 유남성; born March 27, 1957) is a former South Korean professional footballer who played as a defender. He is best known for his career with Daewoo Royals and his participation with the South Korea national team in the 1986 FIFA World Cup.
Born in South Korea, Yu Nam-sung began his professional career in the K League, the top professional football league in South Korea. He spent a significant part of his club career playing for Daewoo Royals (now known as Busan IPark), one of the most successful clubs in early K League history. During his time with Daewoo Royals, he was a key figure in their defense, contributing to the team's successes, including K League titles.
Yu Nam-sung was also a member of the South Korea national football team. He earned several caps for his country and represented South Korea at the highest level of international competition, including the 1986 FIFA World Cup held in Mexico. Although South Korea did not advance past the group stage in that tournament, Yu Nam-sung's participation marked a significant achievement in his career. His dedication and performance made him a respected figure in South Korean football during his playing era.