Over a thousand people participated in dozens of events across Australia to mark the day, with Prime Minister Tony Abbott appreciating Yoga's universal appeal.
"For thousands of years, yoga has provided its followers with a guide to bringing their minds, bodies and spirits into balance.
"Yoga's universal and growing popularity demonstrates its appeal to people from all the walks of life and its great potential to foster better health among individuals and populations around the world," Abbott said.
Yoga events were also held at Sydney's popular Bondi beach and in the Australian capital Canberra.
In the UK, the day began with the main event at the bank of Thames here as hundreds gathered across cities to celebrate the ancient Indian exercise.
British Prime Minister David Cameron said in his message: "The UK is pleased to support International Yoga Day. We were one of 177 countries to vote in favour of Prime Minister Modi's proposal and we are pleased to see the enthusiasm with which it is being embraced, both in UK and around the world."
In China, events were organised at the prestigious Peking University and Geely University where people from different walks of life took part in the exercises.
About a week ahead of the International Yoga Day, the India-China Yoga college was inaugurated at Yunnan Minzu University in Kunming, the first such college in the country.
In Hong Kong, torrential rains lashing the city did not dampen the enthusiasm of people, as more than 2,000 Hong Kongers gathered at the Sun Yat Sen Memorial Park to know the benefits of yoga for health and well-being and also to follow a simple Common Yoga Protocol.
UN Secretary General Ban Ki-moon expressed his excitement at the first International Day of Yoga during his meeting with External Affairs Minister Sushma Swaraj in New York, saying the day has garnered "unprecedented" enthusiasm around the world.
