First ever World Hindi day was celebrated back in 2006. The Prime of India at that time, Dr. Manmohan Singh started this tradition with the aim to popularize the language in other parts of the world.
The first convention to spread Hindi internationally dates back to 1975. World Hindi Day is celebrated every year on 10th January after its inception in 2003.
World Hindi Day need not to be confused with Hindi Diwas. Hindi Diwas is celebrated on 14th September every year to honor the Hindi writers, thinkers and philosophers.
Hindi Diwas came into being as on 14th September, Hindi was adopted as an official language. It also marks the Birthday of Beohar Rajendra Simha, the man because of whom Hindi got global recognition.
Whereas World Hindi Day is celebrated to ensure that the language thrives in other parts of the world and give rise to more Hindi enthusiasts.