The superstar singer has accepted a proposal from her billionaire boyfriend James Packer, after he got down on one knee in New York City and popped the question on Thursday, 21 January.
A rep confirmed the engagement but didn't provide any other details.
According to E! News, however, the diamond engagement ring is "breathtaking" and estimated at 35-carats.
Mariah and James have been dating for around a year , but actually met a few years ago, as she explained on The Steve Harvey Show recently.
"We first met in Aspen. A couple years ago we were at the Hercules premiere. We were talking and laughing and people were getting mad at us and stuff like that. So we hit it off," she said.
"I'm lucky. He really is great."
James, 47, is Australia's fourth richest person with an estimated fortune of £2.3bn, thanks to the media empire he inherited from his father, and his business operations in casinos.
This will be Mariah's third marriage. She was previously wed to music manager Tommy Mottola and America's Got Talent host Nick Cannon, with whom she has twins, Monroe and Moroccan, four.
James has three kids with ex-wife Erica Baxter.
Congrats to Mariah and James!