The new flights are most likely to have corporate and leisure passengers travelling to and from Ranchi and to neighbouring Jamshedpur.
The airline also announced launching of the third daily direct flight from Delhi to Patna.
Ranchi would be the airline's 29th domestic destination.
Announcing the launch of new flights, IndiGo president Aditya Ghosh said, "Ranchi is going to be an important part of our destination network because it holds good prospect for commercial business apart from being the capital city of Jharkhand."
With its fleet of 69 new Airbus A320 aircraft, the airline operates 434 daily flights connecting 34 destinations worldwide.
IndiGo currently operates flights to five international destinations - Bangkok, Dubai, Kathmandu, Muscat and Singapore.