The 'Made In Chelsea' star broke the news the 29-year-old rapper had proposed tonight (25.03.13) on her Twitter and Instagram accounts.
Along with a photo of her ring, she wrote: ''If I could scream loud enough for the whole world to hear I would.''
And her new fiance - whose real name is Stephen Manderson - also commented on the news with a tweet to his followers, joking people need to tell other celebrities he is off the market.
He said: ''Happy days. Someone's gonna have to break the news to Jessica Alba and Eva Mendez.''
The couple began dating in December 2011, and one of Millie's reality TV co-stars recently speculated their relationship has been helped by not broadcasting it on the show.
Binky Felstead said: ''It's easier not working together if you're not in a relationship. It's probably made it easier. I don't know much about them to be honest. I've met him, he's a really nice guy.
''I'm not really one to speak about other people's relationships. They seem very happy together.''