The 23-year-old AC Milan star, who is in Brazil with his country's World Cup squad, also posted a photograph on his Instagram account showing the beach in Rio de Janeiro where he proposed to his sweetheart.
"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," tweeted Balotelli both in Italian and English.
Neguesha, born in Belgium of an Italian father and a mother of Congolese-Rwandan-Egyptian extraction, posted a photograph on Instagram of the star-shaped diamond engagement ring Balotelli gave her.
"Tonight, I said the most important yes of my life. That was the best present for my birthday! I love you first and unique husband." Neither the date nor the place where they will get married was revealed.
Balotelli's next significant date is the opening group game with England in Manaus on Saturday.