She was discovered in the late 1940s, having adopted the name Randall to her surname (she reportedly said it was a favorite uncle's name),[4] by Arturo Toscanini, who engaged her for a series of performances with his NBC Symphony Orchestra in New York City.[3] Toscanini described her at the time as "the find of the century".[2] She appeared as Nanetta in his two-part NBC radio broadcast of Verdi's Falstaff, in 1950, one of Toscanini's most acclaimed performances. It was also released on LP, 45-RPM, and CD.
Stich-Randall travelled on a Fulbright Scholarship to Europe, where she made her name as a singer.[3] She made her European debut in Weber's Oberon in Florence in 1951; she played a mermaid and astonished the audience by singing while she swam in the fountain of the Boboli Gardens. She won a competition in Lausanne the following year. This led to appearances with the Basel Opera in Switzerland. She was a regular performer with the Vienna State Opera and at the Salzburg Festival.[2] From 1955, she was a regular at summer events at Aix-en-Provence in France, where her portrayals of Donna Anna in Don Giovanni and the Countess in The Marriage of Figaro were highly esteemed.[5]
Her career had largely ended by 1980 and she died in Vienna, aged 79, in 2007, of natural causes.[3] She was cremated at Feuerhalle Simmering, where her ashes are buried.[7]