The singer has lost an incredible 70lbs since giving birth to twins six months ago, and the results were there for all to see as she appeared on Rosie O'Donnell's chat show.
After being lowered onto the stage – diva style – in a giant moon, Mariah told Rosie how she did it.
And her bombshell figure, on display in a tight LBD and leather jacket, spoke for itself.
Mariah, who welcomed Moroccan and Monroe on April 30, explained how 40lbs of the weight she shed had been put on due to water retention.
"In the beginning, when I first had the babies, I had so much edema … water and swelling. Most pregnant woman have that just in their feet," said the 42-year-old.
"One day I was doing my thank-you notes and I noticed it started rising up the leg, so I had edema. … I didn't think I would ever be the same person."
Once the singer had shed the water weight, she stared following the Jenny diet plan, of which she's now a spokeswoman.
"The first week, I lost 40 lbs. … of just water," she said. "It was just water, initially. When I started with the program, I lost at least 30 lbs. of weight that needed to be lost."
And it wasn't all just about her appearance. Carrying the extra weight made day-to-day tasks difficult.
"The whole point of this is not just like: 'Oh, hey, look at me and my weight loss, I'm fantastic'," she says.
"I had a really tough pregnancy. I was supposed to be on bed rest, but it was so bad that even bed hurt. … I learned a lot being pregnant, watching my body change."
Since Mariah had a Caesarean section, exercising was out in the first weeks after giving birth.
"The diet is 90 percent of it," she told Rosie.