Reuters reports the deal is the first major investment from Qatar in India, costing US$1.26 billion.
Airtel, which has operations in 20 countries across Africa and Asia and has around 260 million customers, has seen profits fall for the last three years, as a result of competition in India and continuing losses in Africa.
The company is US$11.7 billion in debt, more than twice its operating profits. The company recently raised US$1.5 billion in overseas bonds.
The QFE is an investment vehicle of the Qatar Foundation, controlled by the second wife of the country’s emir. A source told Reuters it planned to be an active investor and would take a seat on the board.
"QFE is in for the long-term," the source said.