After graduation from Dankook University, Back was drafted in the 2010KBO Entry Draft by the Samsung Lions as the 4th pick of the 4th round, 28th overall. In the 2010 Futures League, Back was ranked first in batting average with .306, playing in 106 games. However, Back spent his entire 2010 season in the Lions' second-tier team.
After the 2010 season, Back joined the Korea Armed Forces Athletic Corps Baseball Team to serve a two-year military duty. In October 2011, Back competed in the 2011 Baseball World Cup as a member of the South Korean national baseball team. In the tourney, he shared second base duties with Choi Joo-Hwan but struggled at the plate, batting just .154. The Lions released Sang-won on October 19, 2018.[1]