The patriotic song was adopted as Italy’s provisional national anthem when the nation abolished the monarchy and became a republic in 1946.
No law had subsequently been passed making the decision final until Wednesday.
The anthem is officially known as Il canto degli Italiani, but popularly referred to as L’Inno di Mameli ('Mameli’s Hymn') after the author, or Fratelli d’Italia ('Brothers of Italy'), from its opening line.
The words were written in the autumn of 1847 in Genoa, by the then 20-year-old student Goffredo Mameli.
Two months later, they were set to music in Turin by Michele Novaro.