[1] He trained as an opera singer in Germany, and made his professional debut at the Oper Breslau in 1925 at which time he adopted the stage name Stefan Balla.
[11] He made his United States debut using the name Stefano Ballarini with the Chicago City Opera Company (CCOC) in Ottorino Respighi La fiamma on October 31, 1936.
[14] In July 1937 Ballarini performed the roles of Donner and Alberich in Das Rheingold at Lewisohn Stadium with the New York Philharmonic under conductor Fritz Reiner.
[15] In August 1937 he performed the role of Escamillo opposite Irra Petina as Carmen with the Philadelphia Orchestra under conductor Alexander Smallens at the Robin Hood Dell.
[20] Other parts he performed with the SCOC in 1938 included Amonasro in Aida with Bianca Saroya in the title role,[21] and Germont in La traviata with Mary Henderson as Violetta.
[26][27] In February 1942 Ballarini performed at a meeting of The Verdi Club in New York City; a group founded and organized by Florence Foster Jenkins.
[28] He performed with the Philadelphia La Scala Opera Company (PLSOC) at the Academy of Music as Alfio in Cavalleria rusticana in January 1942,[29] and as Conte di Luna in Verdi's Il trovatore with Bernardo de Muro as Manrico in March 1942.
[30] On November 3, 1942 he created the role of Mr. Martini in the world premiere of Walter Damrosch's The Opera Cloak at the Broadway Theatre in New York City.
[31] In 1943 Ballarini returned to the PLSOC as Escamillo to Jennie Tourel's Carmen,[32] and sang the part of Alfio under conductor Carlo Peroni.
[46] In November 1952 he performed the role of Escamillo to Margery Mayer's Carmen for his debut at the New York City Opera under conductor Joseph Rosenstock.
[2] His recordings include arias from Rigoletto, Un ballo in maschera, and Pagliacci, and the songs "Lolita" by Arturo Buzzi-Peccia and "Visione Veneziana" by Renato Brogi.