Following service in the US Army, he studied at the School of Sacred Music at Hebrew Union College, while at the same time holding a full-time position as cantor at Temple Beth Emeth in Teaneck, New Jersey.

After his graduation in 1953, he served as cantor for the Beth Israel Congregation in Providence, Rhode Island, for three years until moving to Elkins Park, Pennsylvania, where he took up an appointment as the first cantor to the newly built Beth Sholom Congregation[3][4] For several years Schwartzman had also studied classical and musical theatre singing with Robert Weede and eventually received a scholarship to the Academy of Vocal Arts in Philadelphia where he studied under Dorothy di Scala.

The American Opera Auditions prize led to his Italian debut at the Teatro Nuovo in Milan as David in L'Amico Fritz that same year.

On November 12, 1965, Schwartzman made his debut with New York City Opera as Giorgio Germont in La traviata,[8] and remained with the company until 1975, singing leading baritone roles including Lord Nottingham in Roberto Devereux, Scarpia in Tosca, Tonio in Pagliacci, Michele in Il tabarro, Lord Ashton in Lucia di Lammermoor, Marcello in La bohème, Sharpless in Madame Butterfly, and the title role in Rigoletto.

[13][14] His 1973 performance in Sholom Secunda's oratorio Yizkor with Richard Tucker (tenor), Bianca Sauler (soprano), and Howard da Silva (narrator) was broadcast by the ABC television network to mark the 30th anniversary of the destruction of the Warsaw Ghetto.