Career
Baumjohann began his youth career in 1991 with Teutonia Waltrop and joined in summer 2000 Schalke 04. With only two appearances in the first team he moved to Mönchengladbach in January 2007. On 27 January 2007 he made his debut with Mönchengladbach against Energie Cottbus.
In July 2009 he moved to Bayern Munich, but after only half a year with Bayern he joined Schalke 04 again.
On 21 August 2012, Baumjohann joined 2. Bundesliga club Kaiserslautern on a one-year contract.
In Baumjohann"s 27th game for the club, he netted his sixth goal, scoring with a superb free-kick in a play-off versus Hoffenheim for a place in the Bundesliga.
On 8 June 2013, it was announced that Baumjohann would leave Kaiserslautern, who lost to Hoffenheim in their Bundesliga play-off over two legs, for newly promoted Hertha Bachelor of Science, signing a three-year contract with the capital club
On 18 March 2016, he extended his contract until 2017.