The Read All About It hitmaker proposed to the Made In Chelsea regular during a romantic trip to Paris, France on Monday (25Mar13).
MACkintosh took to Twitter.com to reveal the hip-hop star had taken her to her favourite restaurant in the city before asking for her hand in marriage.
She writes, "At my favourite restaurant in the whole wide world and then... If I could scream loud enough for the whole world to hear I would."
She then uploaded a snap of a huge diamond on her ring finger.
Professor Green, real name Stephen Manderson, also tweeted, "Happy days...", and then joked that Hollywood's leading Latinas must be heartbroken he's no longer on the market, adding, "Someone's gonna have to break the news to Jessica Alba and Eva Mendez (sic)."