Alagna's family came from Sicily. He was born in Clichy-sous-Bois, Seine-Saint-Denis, near Paris, France in 1963. When he was a teenager he started singing pop music in Paris cabarets. Later he started to sing in operas. He won the Luciano Pavarotti Voice Competition. He started to sing professionally in 1988 singing the part of Alfredo Germont in Giuseppe Verdi's "La Traviata" with the Glyndebourne touring opera