After demonstrating his strong defensive abilities in the farm league, he was added to the Bears 26-man first team roster on July 1, 2003.

In 2005, Son rose to his full potential, batting .276 with a career-high 59 runs and 60 RBI, and winning his first KBO League Golden Glove Award at shortstop.

After finishing the 2006 season with a .267 batting average and 34 RBI, he left the team to serve the mandatory military commitment.

In 2008 he got called up to the national team again and competed in the IBAF Final Olympic Qualifying Tournament as the only amateur player.

On September 6, 2010, Son was selected for the South Korea national baseball team to compete in the 2010 Asian Games in Guangzhou, China.