Malas made his operatic debut in 1959 in his native Baltimore and in 1960 he won the Metropolitan Opera National Council Auditions. He made his New York debut at the New York City Opera where he came to the attention of Joan Sutherland and her husband, the conductor Richard Bonynge. He was subsequently asked to tour Australia with the Sutherland/Williamson International Opera Company. This led to appearances at London's Covent Garden, the New York Metropolitan Opera (1983–84) and Chicago Lyric Opera.
Hello Malas first performed at the Metropolitan Opera as Sgt. Sulpice in La fille du régiment opposite Dame Joan and Alfredo Kraus. Since then, he has sung there in Il barbiere di Siviglia, La bohème, Les contes d'Hoffmann, Die Fledermaus, Eugene Onegin, L'elisir d'amore, Lulu, Manon Lescaut, Der Rosenkavalier, Salome, Tosca, and Werther. He has also appeared there in two new productions by Sir Peter Hall; as Zuniga in Carmen, and as Dr. Bartolo in Le nozze di Figaro. Mr. Malas has also been seen on the Metropolitan Opera stage as Haly in L'italiana in Algeri opposite Marilyn Horne, and Capulet in Roméo et Juliette.
He has sung leading roles in the major opera houses in Rome, Naples, Salzburg, Vienna, and Florence, has appeared in televised opera, with leading symphony orchestras, and has recorded the operatic repertoire with notables such as Luciano Pavarotti, Beverly Sills, Dame Kiri Te Kanawa, and Sutherland.
A leading bass-baritone with the New York City Opera for many years, he has also sustained a career in television, having appeared in Spenser: For Hire, The Equalizer, Ryan's Hope, One Life to Live, Law & Order and Sex and the City. The New York Times's Frank Rich, commented on Mr. Malas' Drama Desk Award nominated portrayal of the immigrant farmer, Tony Esposito in the Broadway revival of The Most Happy Fella "As acted by Mr. Malas, Tony's inner growth and redemption become the very soul of musical drama, especially as delineated in one gorgeous Loesser song after another."
Malas is married to Marlena Kleinman Malas, a voice teacher in New York. They have two sons, Nicol and Alexis.
- Griselda — Lauris Elms (Griselda), Joan Sutherland (Ernesto), Monica Sinclair (Gualtiero), Margreta Elkins (Almirena), Spiro Malas (Rambaldo), Ambrosian Opera Chorus, London Philharmonic Orchestra, Richard Bonynge, recorded 1967. Decca 448 977-2 (coupled with Montezuma)
- La fille du régiment — Joan Sutherland, Luciano Pavarotti (Tonio), Spiro Malas (Sulpice); Richard Bonynge
- L'elisir d'amore — Joan Sutherland, Luciano Pavarotti, Spiro Malas, Maria Casula; Richard Bonynge
- Semiramide — Joan Sutherland (Semiramide), John Serge (Idreno), Joseph Rouleau (Assur), Spiro Malas (Oroe), Patricia Clark (Azema), Leslie Fyson (Mitrane), Michael Langdon (Spectre of Nino), Marilyn Horne (Arsace), London Symphony Orchestra, Richard Bonynge. Decca 425 481-2, recorded in 1966.