According to E! News, Carey, 30, and Marcus, 28, have officially become parents with a source explaining, “Carey has given birth to a healthy and happy baby.”
“She is just enjoying this time with her family and close friends,” they added.
The Oscar nominee is already back to work promoting her new film Suffragette with Meryl Streep.
She stepped out for the first time since giving birth on Wednesday to attend the British Film Institute’s London Film Festival and the new mum absolutely sizzled on the red carpet.
The Great Gatsby actress looked typically chic in mixed prints and black heels with no hint of the tired eyes a first-time parent usually sports.
She then changed into a breath-taking frilly dress for the film’s opening night.
We first learned of the handsome couple’s pregnancy in June after Carey walked the Tony Awards red carpet in a skilfully-fitted structured dress.
“They weren’t planning on announcing, but she hasn’t stopped working. Everybody around her is being very supportive,” a source told US Weekly at the time.
Marcus and Carey married in 2012 during a secret ceremony in Somerset, England. The pair first met as children when they were each other’s pen pals – truly the cutest love story ever.
“Marcus is the only thing that’s mine that I can keep totally away,” the very private actress told Vogue in May, so no doubt she’ll keep her gorgeous bub under wraps too.
But we might be able to rely on close pal Sienna Miller for details as she can’t stop gushing about her besties – and who could blame her.
“Marcus can headline Glastonbury and Carey can be nominated for however many Oscars, and then they come back to their farm, and they’re in big woolly jumpers and funny hats, raising piglets. It’s an amazing balance they’ve managed to strike. I can’t wait for a little baby to come along,” she told Vogue.