She made her stage debut in Graz in 1945. She joined the Zurich Opera in 1947, where she took part in the creation of Willy Burkhard's Die schwarze Spinne and sang in the local premiere of Stravinsky's The Rake's Progress. In 1952, she began appearing at the Munich State Opera and the Vienna State Opera, her roles there included; Gluck's Orfeo, Verdi's Lady Macbeth, and Judith in Béla Bartók's Bluebeard's Castle. Malaniuk appeared at La Scala in Milan, in the Ring Cycle under Wilhelm Furtwängler. She also made guest appearances at the Royal Opera House in London, the Paris Opéra, the Monte Carlo Opera, at the Salzburg Festival, the Bayreuth Festival in roles such as Magdalene, Fricka, Brangäne, Waltraute, Adelaide and Marina. Malaniuk also enjoyed success in Italian roles such as Dorabella, Vittelia, Azucena, Amneris, she was also active in concert and oratorios, often singing the alto parts in Beethoven's Ninth Symphony and Mozart's Requiem.