Sung-mun Song (born 29 August 1996) is a South Korean professional baseball third baseman for the San Diego Padres of Major League Baseball (MLB). He has previously played in the KBO League for the Nexen / Kiwoom Heroes.
Song debuted for the Nexen Heroes in 2015. He did not become a regular for the Heroes until 2019, and missed the 2020 season and beginning of the 2021 season while fulfilling military service. In 2024, Song was named an All-Star for the first time as well as team captain.
On August 4, 2025, the Heroes signed Song to a six-year contract extension worth â©12 billion. He requested that the Heroes post him to Major League Baseball after the season.
On December 22, 2025, Song signed a four-year, $15 million contract with the San Diego Padres of MLB. The team will also pay for an interpreter and roundtrip tickets from South Korea. Song will receive an additional $1 million signing bonus in two installments.