The idea to have an UN-mandated day for celebrating Yoga was put forward by Prime Minister Narendra Modi during his speech at the United Nations General Assembly (UNGA) in 2014. Later, this proposal was backed by 177 nations which led UN to declare June 21 as International Day of Yoga. The day was incepted in UNGA in 2014.
June 21 was selected as Yoga Day because it is the longest day of year in Northern Hemisphere. It also shares a special significance in different parts of the world.