The real-life couple, along with Jim Carrey, act out the famous holiday story Twas the Night Before Christmas, while a drunk male recites the poem.
Titled as the 'Drunk History Christmas', the Funny or Die clip shows Gosling and Mendes as the parents in the story, with Carrey playing Santa Claus.
Gosling and Mendes were first linked romantically in September when they were photographed together at Disneyland.
In November, they were seen visiting the Pere-Lachaise cemetery in France.
A witness claimed: "They were holding hands and there was a lot of tenderness between them."
Watch the Funny or Die video of Ryan Gosling, Eva Mendes and Jim Carrey below: