Appearing at the premiere of her latest film, Suffragette, the 30-year-old star looked beautiful in this plum-coloured dress so soon after the birth.
The child is her first with her husband, Marcus Mumford, of the band Mumford & Sons.
Although Carey never publicly confirmed the pregnancy, she was seen appearing at several red carpet events sporting a bump earlier this year.
A source told E! News: 'Carey has given birth to a healthy and happy baby. She is just enjoying this time with her family and close friends.'
No news as of yet on the sex or the name, but we'll be keeping our ears close to the ground and letting you know as soon as it's revealed!