In a joint statement, Airtel and ATC announced that they have entered into an agreement "for the sale of over 4,800 of Airtel's communications towers in Nigeria."
Airtel will be the anchor tenant on the portfolio under a lease with a ten-year initial term, it added.
The agreement has been signed between Bharti Airtel subsidiary, Bharti Airtel International (Netherlands) BV (Airtel) and ATC.
ATC in a statement said: "The total consideration is expected to be approximately $1.05 billion (roughly Rs. 6,500 crores), subject to customary adjustments."
"We are pleased to announce the launch of our operations in Nigeria while expanding our relationship with Airtel, one of the leading multinational operators in the world," American Tower President and Chief Executive Officer Jim Taiclet said.
At the end of September 2014, Airtel had a consolidated debt of Rs. 62,215.8 crore.
The deal is expected to be completed in the first half of 2015. The Indian telecom major is looking to sell off its mobile tower asset in Africa and focus on telecom services business only.
"Nigeria is the largest mobile market in Africa and a key one for Airtel. This agreement, which is part of our stated philosophy of promoting infrastructure sharing, will provide us with considerable cost efficiencies and at the same time allows us to sharpen our focus on the customer," Bharti Airtel Africa MD and Chief Executive Officer Christian de Faria said.
Airtel initially had about 15,000 mobile towers across.
In September, Airtel sold about 3,500 telecom towers in Africa to Eaton Towers.