The star, who is best known for her role as Arya Stark in the hit HBO fantasy series "Game of Thrones", will appear on the panel for one episode of the series alongside show stalwarts RuPaul and Michelle Visage.
Comedian Alan Carr and TV host Graham Norton will also join on the panel as alternating judges.
Speaking about her new role, Maisie admitted she's a huge fan of drag and is excited to get to know the contestants on the show.
"What I love the most about drag is the story of the drag queen behind the facade," the 22-year-old shared in a statement. "I think that so much of drag comes from a place of real pain and seeing how that transforms into a character is so interesting to me. I love that about art and about drag."
While the star is the only confirmed guest judge for the new series, last month Britain's The Sun newspaper reported that popstar Cheryl Cole has also been tapped to appear on an episode of the eight-part series.
"RuPaul's Drag Race U.K." will debut on BBC Three later this year.