"I owe it (the award) to my wife, my family, my children and my students," Rao said.
"I was at the airport. An Indigo (airline) employee said that there was an urgent call. It was (about) the Bharat Ratna," Rao told reporters at the Bangalore airport as he arrived from a Kerala trip.
Rao said Prime Minister Manmohan Singh called him on his mobile and congratulated him. "He (Singh) said you have done so much for India and science."
"This (Bharat Ratna) has come as a complete surprise," Rao, who has 60 honourary PhDs to his credit from universities across the globe and enjoys an iconic scientific status in the Indian scientific community, said.
On cricket legend Sachin Tendulkar also being conferred with the Bharat Ratna, Rao said it was his wife who informed him about it. "He is a great player."
"I am a Mysorean. I am proud. I am grateful for this honour to a scientist. We have done a lot of research," Rao said.