He studied in his native Verona with Maria Palanda, and was revealed at the Verdi Competition in Busseto in 1969. He made his official operatic debut the following year in Mantua, as Riccardo in I puritani. Quickly invited to sing at all the major opera houses of Italy, establishing himself as the eminent "Verdi baritone" of his generation, notably in I masnadieri, Luisa Miller, La traviata. He made his debut at La Scala in 1982, as Ford in Falstaff, and took part in important revivals of Attila and I vespri siciliani, under Riccardo Muti.
On the international scene, he appeared in London, Paris, Zurich, Vienna, Barcelona, Lisbon, Caracas, etc. He also sang at the festivals of Orange, in 1982, as Posa in Don Carlo, and Bregenz, in 1985, as Riccardo in I puritani, opposite Edita Gruberova and Salvatore Fisichella.
Zancanaro sang almost every major baritone role of the Italian repertory, but remained incomparable in Verdi roles, in which, his beautiful and evenly produced voice, brilliant upper register, and stylish singing, are shown to best effect. Unfortunately he was largely ignored by the recording companies. All the same, he can be heard and/or seen in the following official recordings:
- Il cappello di paglia di Firenze with Ugo Benelli, Alfredo Mariotti, Viorica Cortez, Daniela Mazzucato RCA 1975
- Il trovatore (video) with Raina Kabaivanska, Franco Bonisolli, Giancarlo Luccardi, dir. Bruno Bartoletti Eurodisc 1975
- Il trovatore with Plácido Domingo, Rosalind Plowright, Brigitte Fassbaender, Evgeny Nesterenko, dir. Carlo Maria Giulini DG 1983
- Don Carlo (DVD) with Luis Lima, Ileana Cotrubas, Robert Lloyd, Bruna Baglioni, dir. Bernard Haitink Castle Vision 1985
- Andrea Chenier with Plácido Domingo, Anna Tomowa-Sintow, dir. Humphrey Burton, Covent Garden 1985
- Andrea Chenier with José Carreras, Eva Marton, dir. Giuseppe Patanè CBS 1985
- La forza del destino with Mirella Freni, Plácido Domingo, Paul Plishka, Sesto Bruscantini, dir. Riccardo Muti EMI 1986
- Madama Butterfly (DVD) with Yasuko Hayashi, Peter Dvorsky, dir. Keita Asart Pioneer Artist 1986
- Guglielmo Tell with Chris Merritt, Cheryl Studer, Luigi Roni, dir. Riccardo Muti Philips 1988
- Rigoletto with Daniela Dessì, Vincenzo La Scola, Paata Burchuladze, dir. Riccardo Muti EMI 1988
- I vespri siciliani with Chris Merritt, Cheryl Studer, Ferruccio Furlanetto, dir. Riccardo Muti EMI 1989
- Attila (DVD) with Samuel Ramey, Cheryl Studer, Kaludi Kaludov, dir. Riccardo Muti Fonit-Cetra 1991
- La traviata (DVD) with Edita Gruberova, Neil Shicoff, dir. Carlo Rizzi Teldec 1992
- Tosca with Carol Vaness, Giuseppe Giacomini, dir. Riccardo Muti Philips 1992
- Le guide de l'opéra, les indispensables de la musique, R. Mancini & J-J. Rouveroux, (Fayard, 1995), ISBN 2-213-59567-4
- Nina Debrunner (2005). "Giorgio Zancanaro". In Andreas Kotte. Theaterlexikon der Schweiz (TLS) / Dictionnaire du théâtre en Suisse (DTS) / Dizionario Teatrale Svizzero / Lexicon da teater svizzer [Theater Dictionary of Switzerland] (in German) 3. Zürich: Chronos. p. 2136. ISBN 978-3-0340-0715-3. LCCN 2007423414. OCLC 62309181.