Originally, the Red Bull protege was not going to drive in the race--his original contract did not include it. However, the Spanish-owned team has asked driver Tonio Liuzzi to step aside instead.
HRT boss Colin Kolles said: "Narain is a talented driver and we are proud to be going down this path with him. For this single event, Narain will be driving alongside Daniel Ricciardo. I have asked Tonio Liuzzi to step aside for the Indian GP in order to allow driving programs with Ricciardo and Karthikeyan to be completed. I have to thank Tonio for his professional approach and attitude."
Karthikeyan said: "Driving in front of the home crowd cheering on is going to be a surreal experience. A once in a lifetime experience, and I feel extremely fortunate. There is a huge buzz around the grand prix already and I'm sure that it'll be a resounding success that will motivate more youngsters toward the sport and give us the future F1 drivers.
"Making it into F1 at the time I did was a seriously uphill task and the thought of being able to compete in the inaugural Indian GP was non-existent. But it is finally here and I'll be on the grid. It is going to be one of the most challenging circuits on the calendar.
"There are points at which, if you're in an F1 car, you will see nothing but the sky. The layout itself is going to put tremendous energy through the tires and the strategy will play a key role in the final result. For sure I'll race hard and try to get a good result for myself and the team."