The 23-year-old proposed to the model in Brazil at the beginning of the week – five days before the Azzurri face England in their Group D World Cup opener in Manaus.
Balotelli revealed the news on the social network site on Tuesday along with a picture of Neguesha wearing an engagement ring.
The AC Milan striker wrote: “She said yes.. The most important yes in my life. That was the place of my question! I Love you and happy birthday too ! Je t'aime my WIFE”.
The former Manchester City forward has been dating the Belgian model since 2013, although they briefly split last year before rekindling their romance.
Balotelli's team, Italy, will take on Roy Hodgson's England side before facing Costa Rica and Uruguay at the World Cup in Brazil this summer.