The county now has 13 such beaches which have to reach high standards for visitors.
This is the highest in the country alongside Kerry and Mayo.
The county had 12 flags last year and now Downings has been added to that list.
Mayor of Donegal Noel McBride said he was delighted with the news.
“I hope we can add even more Donegal beaches to that in the future.
“I am particularly proud that the latest beach to get the Blue Flag status is Downings which is in my constituency,” he said.