When he returned to India in 1962 after turning down a job with IBM on the advice of JRD, he was sent to Jamshedpur to work on the shop floor at Tata Steel with other blue-collar employees, shovelling limestone and handling the blast furnace. In 1971, he was appointed the Director of National Radio and Electronics (Nelco), which was in dire straits when he came on board: with losses of 40% and barely 2% share of the consumer electronics market. However, just when he turned it around (from 2% to 25% market share), the Emergency was declared. A weak economy and labour issues compounded the problem and Nelco was quickly near collapse again.
For his next assignment, in 1977 he was asked to turn around the sick Empress Mills, which he did. However, he was refused a Rs 50 lakh investment required to make the textile unit competitive. Empress Mills floundered and was finally closed in 1986.
In 1981, JRD Tata stepped down as Tata Industries chairman, naming Ratan as his successor. He was heavily criticized for lacking experience in running a company of the scale of Tata Industries. In 1991, he was appointed group chairman of the Tata group. As group chairman, he has been responsible for converting "the corporate commonwealth" of different Tata-affiliated companies into a cohesive company. He has been responsible for the acquisition of Tetley,Jaguar Land Rover and Corus, which have turned Tata from a largely India-centric company into a global business, with 65% revenues coming from abroad. He also pushed the development of Indica and the Nano. He is widely credited for the success of the Tata Group of companies, especially after the liberalization of controls after the 1990s.
In August 2007, Ratan Tata lead Tata Group's acquisition of British steel maker Corus. At that time, this was the largest takeover of a foreign company by an Indian company, and resulted in Tata Group becoming the fifth largest steel producer in the world. According to the BBC, however, some analysts criticized the move, saying that Tata Group had overpaid for Corus and had prioritized national pride before its shareholders. Tata is set to retire in December 2012 to be succeeded by Cyrus Mistry, the 42-year-old son of Pallonji Mistry and managing director of Shapoorji Pallonji Group.