The 86-year-old industrialist said on Monday that he was undergoing routine medical evaluations due to his age and related health concerns.
In a social media post the same day, Tata assured that he remained in good spirits and emphasised that there was no cause for alarm.
Ratan Tata took over as chairman of the autos-to-steel conglomerate in 1991, leading the company, established by his great-grandfather over a century ago, until 2012.
He also founded Tata Teleservices in 1996 and oversaw the public listing of Tata Consultancy Services in 2004.
After his retirement, he was honored with the title of chairman emeritus for Tata Sons, Tata Industries, Tata Motors, Tata Steel, and Tata Chemicals, according to the company's website.