The 26-year-old Chennai-born driver will partner Brazilian rookie Bruno Senna at the cash-strapped team, who have changed their name from Campos Meta, when the season starts in Bahrain next week.
"We have been very impressed with Karun's performance in GP2," said team principal Colin Kolles. "It will be great for the sport to have an Indian driver on the grid for the first Indian Grand Prix." India, with a circuit under construction near New Delhi, is due to make its debut on the race calendar next year.
The only other Indian driver to have raced in Formula One was Narain Karthikeyan for the Jordan team, at the time also run by Kolles, in 2005.
Chandhok also partnered Senna, nephew of the late triple world champion Ayrton, in the GP2 support series.
HRT, also known as Hispania Racing F1 team, changed their name this month after Campos were bought by Spanish businessman Jose Ramon Carabante.
The Cosworth-powered car, which has not been tested ahead of the March 14 season opener, was unveiled on Thursday in the southeastern city of Murcia where the first Spanish F1 team will be based.
