[6] He is the eldest son of Franco Mentana, well-known correspondent of La Gazzetta dello Sport and native of Bova,[2] and Lella, of Jewish origins.

[2] He grew up in Milan's district of Giambellino, he attended the Liceo Ginnasio Alessandro Manzoni, first joining the small anarchist group Movimento Socialista Libertario,[9] in 1968, and then the Italian Socialist Party.

He collaborated and then became director of the magazine Giovane Sinistra,[4] the official organ of the Federation of Young Socialists (Federazione Giovanile Socialista Italiana), of which he was vice-president from 1977 to 1979.

He made a swift career in the company, which led him to be the anchor of the mid-evening edition of TG1 first and then editor-in-chief of the weekly TV documentary Speciale TG1, taking over from Alberto La Volpe.

[6] In 1987, he refused the request from Bettino Craxi, the leader of the Italian Socialist Party, to be the main spokesperson for a political commercial; the spot was characterized by the motto "Perhaps a carnation would be good for you too" ("Forse un garofano starebbe bene anche a voi").

On 13 January 1992, together with the journalists Lamberto Sposini, Clemente J. Mimun, Emilio Carelli, Cesara Buonamici and Cristina Parodi, he started TG5, Canale 5's newscast.

"[12] TG5's audience often exceeded seven million listeners and beat TG1 in viewership several times, making Mentana one of the best-known TV hosts in Italy.

The first time it happened was with the breaking news edition announcing the murder of the judge Giovanni Falcone); other notable events were the interview with Farouk Kassam [it], 7-year-old child kidnapped in 1992, and the confrontation between Silvio Berlusconi and Achille Occhetto before the 1994 Italian general election.

In 1994, Mentana criticized the choice of the dismissal of Indro Montanelli from Il Giornale[13] giving first the news and interviewing him live on TG5 on the same day.

On the occasion of the 2008 Italian general election, he interviewed the candidates for prime minister Walter Veltroni and Silvio Berlusconi in a prime-time edition of Matrix.