Varadarajan will be leaving the Delhi-headquartered airline after completion of his notice period, which ends this month.
A Vistara spokesperson confirmed the developments.
"Yes, he has resigned," the spokesperson said adding that he will remain with Vistara till December 31.
Varadarajan has been with the Tata group since 1996, when he joined the Tata Teleservices Ltd (TTSL) start-up team.
Prior to moving to the Tata Sons and Singapore airlines joint venture, he was serving as executive vice-president for Human resources with TTSL.
The airline had started operations in January 2015.
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