"What I am fighting for is to save the soul of the Tata Group," Mistry said in a letter to the shareholders of TCS on Tuesday.
The company has called the EGM to decide whether or not to remove Mistry as a Director from its board.
Tata Sons had earlier asked Mistry to follow his own assertions on corporate governance and step down from the boards of Tata companies.
Tata Sons board had ousted Mistry on October 24 and appointed Ratan Tata as the interim Chairman.
"Whatever be the decibel level of the voice that would drown your vote, I call on you to vote with your conscience and send a signal that catalyses a larger discussion on governance reform, to save the very fabric of what we have all inherited -- the Tata values that our founders handed us," Mistry said.
Mistry in his letter pointed out: "Over the past several weeks, many have tried to mischaracterise my refusal to go without resistance, as a measure of: (a) retribution for how I was treated at Tata Sons;(b) a fight for control over operating companies; or (c) a hankering for office - a desire to reclaim a position."
However, denying the allegations, Mistry said: "None of the above is true. The fight is a matter of principle rather than facing the foregone outcome."
He elaborated that the very future of TCS 'hinges on good governance and ethical practices'.
"That can flow only from the promoter and needs to permeate into the Board and Management," Mistry explained.
"In the past several weeks, we have seen good governance being thrown to the wind in every sense of the term, replaced by whims, fancies and personal agenda. We have witnessed an unmatched erosion of ethical values and the very foundation of the institution being put to grave risk by the conduct of a few."
Nevertheless, Mistry added that since the requisitionist's stake in the equity share capital of the company is over 73 per cent, the outcome of the EGM is a foregone conclusion.