Tata, however, will serve as honorary chairman emeritus and remain chairman of the various Tata trusts.
The second person without the Tata surname to head the group after Nowroji Saklatwala, Mistry has been working as deputy chairman of the company since November last year.
The five-member search committee set up in August 2010 to select the chairman of the group, zeroed in on Mistry from a reported shortlist of five.
The new chief, whose family owns 17% — the largest individual shareholding — in Tata Sons, was earlier managing director of Shapoorji Pallonji Group, India’s second largest infrastructure company.