However, the carefully developed plan was laid aside on 17 November 1950, when Nadine Connor was too ill to sing the part of Zerlina, the soubrette role in Mozart's Don Giovanni. Peters was asked, virtually at the last minute, to substitute, and made a sensation.
She immediately became a star and a mainstay of the Met, and one of America's most beloved classical musicians. She remained on the active roster of the Met for more than 35 years, the longest tenure of any female singer in the great house's history. She sang over 500 performances in more than 20 roles.
Peters specialized in sparkling roles best suited to her special vocal quality (which Martin Bernheimer said possessed "considerable charm and flute-like accuracy") -- Gilda, Despina, Norina, Rosina, and Lucia di Lammermoor. When in later career her vocal quality broadened she also took on lyric soprano roles such as Mimi and Violetta.
She did not confine her appearances to the Met. She debuted at Covent Garden in 1951 in Balfe's The Bohemian Girl, conducted by Thomas Beecham, in various opera houses in Germany and Austria (including the Salzburg Festival), in San Francisco and Chicago and in Russia's Bolshoi and Kirov opera houses.
She was also active on television in an age when American television networks had classical music programs and the main variety shows included featured classical artists. She held the record for highest number (65) of guest appearances on CBS's The Ed Sullivan Show. She made 25 appearances on the Voice of Firestone. As such, she was one of the most effective ambassadors of classical music to the general population, assisted by an appealing all-American personality. She also appeared in films and sang Broadway musical numbers with a good sense of their style.
She was honored as the 1964 Federation of Women's Clubs' Woman of the Year, won the Bolshoi Medal from the Bolshoi Opera of Moscow in 1972, and in 1997 was one of the Jewish Cultural Achievement Awardees, cited for "her talent, her charm, and her commitment to the arts as well as to the Jewish people." She established a Roberta Peters Scholarship Fund at the Hebrew University in Tel Aviv, and received numerous honorary degrees. In 1991, President Bush appointed her to the National Council of the Arts, and she served as member of the Boards of the Metropolitan Opera Guild and the Carnegie Hall Corporation.
She gave master classes, including a series in the People's Republic of China. In 2000, Peters received the Handel Medallion. The honor, presented to her by Mayor Rudolph W. Giuliani is a tribute to individuals who have enriched New York City's cultural life. Peters died in early 2017 at her home in Rye, New York, as a result of Parkinson's disease.