Yellowstone, which became the world's first national park in 1872, was designated as imperiled by UNESCO in 1995.
At the time, a proposed gold mine near the 3,475-square-mile park's northeastern corner in Montana had raised concerns of ecological damage.
The United Nations Educational, Scientific and Cultural Organization said in a statement that it was giving the park a clean bill of health after the mining project was abandoned and progress was achieved in handling other essential issues.
The National Parks Conservation Association, an advocacy group, earlier this year listed Yellowstone among the 10 most endangered parks in the United States. The group said the park, which is largely in Wyoming but also touches Montana and Idaho, faces problems from air pollution and noise from snowmobiles.
But Elaine Sevy, a spokeswoman for the National Park Service, said then that the administration but does not agree with the snowmobile complaint, saying it can be safely managed using the latest technology.
Also at a meeting Wednesday, UNESCO struck from its endangered list park areas in Bulgaria and Serbia and Montenegro.