The other names in the running were Miss India Neha Dhupia, actor Shahid Kapoor, Sonu Sood, southern star Dhanush, Kareena Kapoor and veteran actress Hema Malini.
Bachchan, 70, has been named the hottest vegetarian celebrity three times in the past and even won the crown in PETA Asia's equivalent contest last year.
Balan, who has won the crown in 2010, too has often credited her curves to her meat-free diet, saying, "I am a vegetarian, as a result my metabolism has improved and this is a huge contributor to weight loss."
More and more of India's hottest stars are choosing to keep meat off their plates and when you look at Amitabh and Vidya, it is easy to see why," said Poorva Joshipura, CEO, PETA India.