Cyrus Mistry has resigned from the boards of all Tata Group companies, in the latest twist in a bitter management feud.
His move came ahead of several extraordinary general meetings, which had been called to remove him.
However, Mr Mistry said he would pursue “governance reform” at Tata, and work to “regain lost ethical ground”.
Mr Mistry was ousted as chairman of holding company Tata Sons by the board in October.
He had led the conglomerate since December 2012.
When the holding company unexpectedly replaced Mr Mistry with his predecessor Ratan Tata on 24 October, it gave no explanation or details about its decision.
But analysts said there had been a clash over strategy, with the Tata family unhappy at Mr Mistry’s policy of looking to sell off parts of the business – including Tata’s European steel business – rather than holding on to assets and extending the firm’s global reach.
Tata Sons subsequently moved to force Mr Mistry out of all parts of the business.
It had called four extraordinary general meetings for this week to remove Mr Mistry from the boards of Tata Steel, Tata Motors – whose brands include Jaguar Land Rover – Tata Chemicals and Indian Hotel Group.
In his letter of resignation to shareholders on Monday, Mr Mistry said the events of the past eight weeks had been about saving a legacy. “A legacy of values and ethics inherited from the founder of the Tata group, Jamsetji Tata”.
He said that: “Unknown to the outside world, I had confronted and was grappling with serious governance problems and ethical issues for a considerable period of time.”
Mr Mistry said it was now time to “shift gears, up the momentum and be more incisive in securing the best interests of the Tata Group”, which was why he had decided to step down.
Tata Sons is one of India’s oldest conglomerates and is made up of more than 100 companies, including Tata Motors, Tata Power and the IT giant, Tata Consultancy Services.
In a statement, it said Mr Mistry’s resignation was a “deliberate strategy on his part, knowing fully well that the overwhelming majority of the shareholders were not in support of his actions”.
The holding company went on to say that Mr Mistry continued to make “baseless, unsubstantiated and malicious allegations”.
Mr Mistry had been a director of Tata Sons since 2006, it added, and had been fully involved in all key decisions.