The Mask star has been dating the model-turned-actress for four years and the pair has lived together since 2008 with seven-year-old Evan.
And McCarthy is full of love for Carrey - because he makes sure her son enjoys the festive period by putting on his famous funny impressions.
She says, "He puts the presents under the tree, eats the cookies and does a ho-ho-ho dance. It's one of the most glorious things to see the man you love do that. But also, it's Jim Carrey, possibly the best mimic in the world."