Kang attended Pocheol Technical High School in Pohang, Gyeongsangbuk-do, South Korea. In 2003, he was selected for the South Korea national junior team and competed in the 5th Asian Junior Baseball Championship held in Bangkok, Thailand. As a starting catcher, Kang helped South Korea win their second Championship title.
After graduation from high school, Kang made his pro debut in 2004, drafted by the Lotte Giants in the 2nd round (3rd pick, 17th overall) of the 2004 KBO draft.
In the 2006 KBO season, he became a starting catcher, appearing in all 126 regular season games. Kang was the youngest starting catcher to play all regular season games in the KBO history.
Kang offensively broke out in the 2008 season. He finished 19th in batting average (.292), 5th in home runs (19) and 6th in RBI (82), and led the Giants to their first post-season appearance since 2000. He won his first Golden Glove Award. Kang was the first catcher of all time to win a Golden Glove Award as a Giants catcher.