كتب : Hatem Maher
The 22-year-old, who joined Bayern in the close season after his contract with Borussia Monchengladbach expired, spent just six months with the Bavarian giants.
"The attacking midfielder has put pen to paper on a deal that will keep him in Gelsenkirchen until 30 June 2013," Schalke said in a statement on their official website.
"No details of the transfer fee will be released."
Baumjohann made three appearances in the Bundesliga and one in the German Cup with Bayern.
He began his career with Schalke before moving to Monchengladbach in January 2007.