D'Alessio was born in Naples. Well known in Naples beginning in the early 1990s and throughout Italy due to participation in the Sanremo Festival in 2000 and 2001. He has also made overseas appearances, the most recent is in Malta 7th July 2012. He lives in Rome with the popular Italian singer Anna Tatangelo, who is two decades younger than him. Previously, he was married to Carmela Barbato, with whom he has three children. He frequently writes and produces songs for Tatangelo, and some of the hits he had a hand in writing include "Quando due si lasciano" and "Ragazza di periferia". For Tatangelo's latest album, the couple penned the songs "Averti qui" and "Lo so che finirà" together. The couple have recorded two duets: "Un nuovo bacio" and "Il mondo è mio". They also toured the US and Canada together in October, featuring in successful concerts. He was the writer and composer of Tatangelo's song performed at Sanremo Music Festival 2008, "Il mio amico".
D'Alessio achieved international success with his recent single "Un cuore malato", a duet with Belgian-