The husband and wife duo, who release a Christmas album later this month (Nov16), will play America's annual National Christmas Tree Lighting ceremony in Washington, D.C. on 1 December (16).
Also added to the bill at President's Park, the estate in which the White House sits, are folk rockers The Lumineers.
They will join the artists already announced; James Taylor, Chance the Rapper, Kelly Clarkson, and Yolanda Adams in performing a collection of festive songs at the event.
In addition to headlining the White House holiday gig, Garth and Trisha will also help Dolly Parton light up the Christmas tree at New York City's Rockefeller Center later this month.
This year's ceremony, the 94th in total, will be the last of U.S. leader Barack Obama's presidency, as President-elect Donald Trump will move into the White House in January.
The National Christmas Tree Lighting ceremony will be televised on Hallmark Channel on 5 December (16).