The 32-year-old centre back, who went out on loan to Russia's Anzhi Makhachkala in February, had agreed a two-year contract, Leverkusen said on their website - but no fee was mentioned although the deal is believed to be in the region of 3 million.
"Emir Spahic is skillful and strong in challenges," Leverkusen sporting director Rudi Voeller said.
"He also has outstanding technical ability and is very good in the air," added the former German international.
"He'll help us to achieve our targets in the Bundesliga, the German Cup and, of course, the Champions League."
- Sports & Recreation
- Anzhi Makhachkala