"We're glad that our bid to be part of the ISL has been accepted. A lot of time and thought has gone into our decision of wanting to be part of the Indian Super League," Bengaluru FC CEO Parth Jindal said in a statement.
"The biggest factor has been the interest of the long-term future of Indian football. A longer league is the right road ahead."
The second team are based in the city of Jamshedpur in the eastern state of Jharkhand and are backed by Tata Steel Ltd, a subsidiary of the Tata Group. The team have not been named yet.
Promoted by billionaire Mukesh Ambani's Reliance Industries and Rupert Murdoch's Star India TV, the ISL has grown in popularity and gained ground on the I-League since it was launched in 2014.
(Reporting by Simon Jennings in Bengaluru; Editing by Clare Fallon)