Monthly rates will be announced shortly before the phone goes on sale, T-Mobile Chief Executive Hamid Akhavan said.
He declined to give a sales target or details on any revenue-sharing deal with the U.S. consumer electronics group.
Asked about sharing revenue with Apple , Deutsche Telekom Chief Executive Rene Obermann also declined to give details but said: "We are not doing this just for image reasons. We need to get serious about making the Internet mobile, and entering partnerships such as the one with Apple is one way."
Akhavan declined to be drawn on any plans to sell the iPhone in other countries where T-Mobile is active, saying: "Right now we are only talking about Germany."
As in the United States, where Apple picked top telecoms operator AT&T in an exclusive deal, customers in Germany will have to sign up for two years for the 8-gigabyte phone. It will be available exclusively in T-Mobile shops.
Reuters reported last week that T-Mobile had landed the coveted deal.
Asked how the iPhone would fare relative to rival devices from Samsung or Nokia , Akhavan said he was not worried.
"I think what Apple has done is way ahead of the competition ... This is not just a phone, it's the best iPod they have ever made," Akhavan said.
Apple Chief Executive Steve Jobs said he was delighted to work with T-Mobile, adding that he hoped the deal would continue for many years.