Prime Minister Modi did stretches, bends and breathing exercises with 35,000 school children,people and soldiers.
Millions of others are expected to do yoga at similar events planned in hundreds of Indian cities and towns.
Prime Minister Modi, a yoga enthusiast who says he practices the ancient Indian art daily, lobbied the United Nations to declare 21 June International Yoga Day last December.This initiative was supported by 177 countries which is an international record.
Thousands of colourful mats were laid out on Rajpath where the main event was held.
Authorities said more than 37,000 people attended the 35-minute yoga session on Rajpath, aimed at setting a new Guinness World Record for the largest yoga class at a single venue.