The Serbian has signed a contract valid until 30 June 2018 and will help plug a gap left by a serious injury to Jakub Blaszczykowski.
Jojic was recently voted as the best player of the first season half in his homeland after netting six goals and providing seven assists in 15 matches. The 21-year-old, who will not feature in Dortmund's squad against Braunschweig on Friday night, made his senior international debut for Serbia in October 2013 against Japan, crowning his display with a goal.
"We're delighted to have signed a versatile midfielder in Milos Jojic. He completes our squad," said Dortmund sporting director Michael Zorc.
"I'm happy to be able to play for such a great club like Borussia Dortmund," Jojic told bvb.de. "I'm looking forward to playing in the Bundesliga and in the Champions League."