His work in the theatre as writer and actor is also widely appreciated; together with Sandro Luporini he pioneered the musical genre "teatro canzone" ("song theatre").
The new underground auditorium of the Pirelli Tower in Milan is dedicated to him.
Following from this he began to frequent the Santa Tecla, a venue in Milan where he had the chance to meet the most well-known and promising musicians of the time, including Luigi Tenco, Gianfranco Reverberi, Adriano Celentano, Ricky Gianco, and Mogol, who obtained a contract for Gaber with Dischi Ricordi. He then played with the Rocky Mountains Old Time Stompers (replacing Tony Dallara who had left to pursue a solo career) and with Rolling Crew.
Because neither Tenco nor Gaber were yet registered with the Italian Society of Authors and Editors they could not trademark the song "Ciao ti dirò" ("I'll Say Hi to You", inspired by Elvis Presley's "Jailhouse Rock"), so it was signed off by Giorgio Calabrese and Giampiero Reverberi although in reality composed by Tenco and Gaber.
The two went on to continue writing music together, developing at the same time a close friendship. In 1958 they toured Germany together with Adriano Celentano, Enzo Jannacci, Paolo Tomelleri e Gianfranco Reverberi.
Gaber paired up with Enzo Jannacci as I Due Corsari ("The Two Privateers"), who made their debut at the end of 1958 with two vinyl singles - "Come Facette Mammeta", a classic song of Neopolitan humour, and "Non occupatemi il telefono" ("Don't Hog the Telephone"). They continued to release singles with Dischi Ricordi throughout the following year, and in 1960 released their first album, Giorgio Gaber - Enzo Jannacci.
After a sentimental-artistic companionship with singer and actress Maria Monti he married Ombretta Colli in 1965, then a student of languages (Chinese and Russian) at the University of Milan.
He participated four times in Sanremo, with the songs "Benzina e cerini" ("Petrol and Matches") in 1961, "Così felice" ("So Happy") in 1964, "Mai, Mai, Mai Valentina" ("Never, Never, Never Valentina") in 1966 and "...E allora dai" ("...Well Come On Then!") in 1967.
In 1974 he was given the Premio Tenco in the first edition of that musical review. He also received the Targa Tenco in 2001 for his song "La razza in estinzione" ("The Dying Race") and in 2003 for the album Io non mi sento italiano ("I Don't Feel Italian").
Giorgio Gaber died, after a long disease, the 1 January 2003 in his country house in Montemagno near Camaiore (Lucca, Tuscany). He is interred in the Cimitero Monumentale in Milan.
There is also a large discography of LPs and 45s related to his production of pop music songs and ballads.