After Kumar turned in his papers, he received praise from several people including IndiGo's Interim CEO Rahul Bhatia, who said that Kumar's contributions had been crucial "in getting us to the level we are today".
Meanwhile, Kumar said that his 12-year stint at IndiGo had been the "most satisfying and rewarding experience" of his career.
IndiGo's shares fell by 2% after Kumar's departure
IndiGo, which has a fleet of 160 aircraft and operates over 1,000 flights daily, had, in April, announced the departure of Aditya Ghosh, its President and Whole Time Director.
Following the announcement of Kumar's departure, shares of IndiGo's parent, InterGlobe Aviation, declined by nearly two percent to trade at Rs. 1,164.55 during the afternoon at the Bombay Stock Exchange (BSE).