The GNO Chorus was founded at the same time as the opera company, then a department of the Royal Theatre. Comprised of professionals, it has also served as a launching pad for singers who went on to build international careers, such as Nikos Zachariou, Costas Paschalis, Kiki Morfoniou and Dimitris Kavrakos. Its extensive repertory covers four centuries of opera, operetta, choral works and works of ecclesiastical music.

The GNO Chorus has gone on tour in Greece, Cyprus, Turkey and Australia, and has also participated in all the big productions with which the GNO traditionally inaugurates the Athens Festival and the Epidaurus Festival. It has worked with acclaimed Greek and foreign conductors, while the position of coach and director has been held successively by Elli Nikolaidou, Michalis Vourtsis, Petros Tzaferis, Fani Palamidi and Nikos Vasileiou, and is currently held by Agathangelos Georgakatos.