However, when a principal on the main company tour was taken ill she sang Rossini’s title role for them in the full staging at a few days notice.
The years following saw her appear as the page in Salome in Chicago, Varvara in Káťa Kabanová in New York, Dorabella at Glyndebourne, Rosina at the Opéra-Comique in Paris and Mercédès in Carmen at the Opéra Bastille.
Her other appearances on the opera stage have included La Monnaie in Brussels and the Netherlands Opera (Cherubino); Glyndebourne Festival (Dorabella); the Opéra National de Paris (Dorabella and Meg Page in Falstaff); the Opéra-Comique (Rosina and the title role in Carmen); Welsh National Opera (Octavian, Sesto, Angelina in La Cenerentola, Rosina, Cherubino, and the title role of Gluck's Orfeo ed Euridice); and the Théâtre du Châtelet in Paris (the title role in La Belle Hélène and Sesto in Giulio Cesare).
Engagements have included the Proms in London, the Salzburg and Edinburgh Festivals, a concert at the Buckingham Palace with Franz Welser-Möst, concerts with Seiji Ozawa in Tanglewood, Berlioz's La mort de Cléopâtre in the Amsterdam Concertgebouw, Schoenberg's Gurrelieder in Düsseldorf and Elgar's The Dream of Gerontius in Madrid and Barcelona.
[14] In May 2021, Karnéus was one of 10 new members elected to the Royal Swedish Academy of Music, alongside Marika Field, Richard Sparks, Jonas Knutsson, Sten Sandell, Đuro Živković, Keiko Abe, Giancarlo Andretta, Stefan Dohr, and Quincy Jones.