From April 2009 to December 2010, Kim was a cast member of Invincible Baseball Team, a variety-reality show that aired during Saturday Challenges; he was chosen as MVP for several weeks.

In July 2009, he made his stage debut in the musical Youthful March (젊음의 행진), along with his T-Max co-member Park Yun-hwa.

A representative from his agency Planet05 commented, "Kim Joon has taken an interest in spreading Korean culture after he was able to meet with various international fans and after being named as an honorary ambassador of Global Tourism Etiquette.

On May 16, 2011, the T-Max members appeared on the game show 1 vs. 100 to raise funds for the establishment of an "invincible baseball" team; Kim advanced to the final 2, but did not win.

Kim enlisted for his mandatory military service on September 29, 2011 for four weeks of basic training, followed by duty as a conscripted policeman.