Olivero began her career taking unfruitful auditions for Italian radio. Eventually accepted as a pupil by Luigi Gerussi, she finally made her radio debut in 1932 as Mary Magdalene in Cottozzo's rather obscure I Misteri Dolorosi. After further studies in Turin, Olivero made her first stage appearance as Lauretta in Gianni Schicchi at the city's Teatro Victorio Emanuele. A 1934 La Scala debut as Anna in Nabucco was followed by an engagement with a company touring the Italian peninsula. In 1937, she returned to Turin, this time to the Teatro Carignano, and was acclaimed in Monteverdi
's Il Combattimento di Trancredi e Clorinda. Word traveled quickly about the gifted young soprano, and that same year she recorded Liu to Gina Cigna
Marriage and retirement in 1941 kept her largely away from the public, but when she returned to the stage a decade later, she resumed a performing career that carried her into old age. In addition to such verismo roles as Adrianna, Tosca, Fedora, and even Minnie in La fanciulla del West, she also devoted herself to contemporary works. She appeared in London as Mimi in 1952 during an Italian season at the Stroll Theatre. Her Adrianna at the 1953 Edinburgh Festival brought more warm reviews. When she made her American debut as Cherubini
's Medea at Dallas in 1967, audiences who had known her only as a name were transfixed by her singing and acting. A Metropolitan Opera debut came in April 1975, after which Olivero sang the role nine more times in the house and on tour. When in her early eighties, she recorded major scenes from Adrianna Lecouvreur; her always slender, rather reedy voice was reduced in size, but still guided by all the conviction, crystalline diction, and unfaltering legato that were her hallmarks.