Here's a chart that shows what day Earth Day is celebrated from 2014 - 2021. Earth Day is celebrated around the world on April 22. Some cities start celebrating a week in advance, ending the recognition of Earth Week on April 22nd. Others host month long events to stress the importance of teaching about our environment. The United Nations celebrates Earth Day each year on the March equinox, which is often March 20, a tradition which was founded by peace activist John McConnell in 1969.