Sarah Silverman and Michael Sheen made their first joint red carpet appearance at the Met Gala in NYC on Monday, May 5. Credit: Dimitrios Kambouris/Getty Images

It doesn't get more official than the Met Gala! Sarah Silverman and boyfriend Michael Sheen made their first joint red carpet appearance at the Metropolitan Museum of Art's Costume Institute Gala in New York City, on Monday, May 5.

Silverman, 43, looked super glam in a strapless bordeaux-colored duchess satin ball gown by Zac Posen. The comedienne told Us Weekly that her gorgeous oxblood dress felt "like f---ing second skin!" on the red carpet.

Sheen, 45, also cleaned up well in a white silk lapel tuxedo jacket and black mohair pants by Prada.

Us exclusively confirmed Silverman and Sheen were dating back in February 2014. The two stepped out together one month later in Manhattan, where they were photographed holding hands.

Vogue.com Photos: Best Met Gala gowns of all time!

Interestingly enough, Sheen's ex-girlfriend Rachel McAdams was also at the Met Gala Monday evening. The Notebook actress looked pretty in a pale pink silk cady evening dress by Ralph Lauren, which featured a gorgeous chiffon train.