She appeared at La Scala in Milan as Diane in Gluck's Iphigénie en Aulide, and returned in 2004 to perform in Salieri's Europa riconosciuta, conducted by Riccardo Muti.

[5] She performed the soprano solo in Ein deutsches Requiem by Brahms, conducted by Nikolaus Harnoncourt, with the Arnold Schoenberg Choir and the Vienna Philharmonic at the Musikverein.

[6] In November 2007, Kühmeier made her U.S. debut as Pamina at the Metropolitan Opera in New York, conducted by Kirill Petrenko.

[7] She recorded the solo in Mahler's Fourth Symphony live with the Münchner Philharmoniker, the orchestra that had played the premiere, conducted by Valery Gergiev.

A critic noted: "Kühmeier's endearingly fresh and expressive singing of the child's innocent vision of heaven is admirable.