[6] In 1998, her Rosina in The Barber of Seville at the Royal Opera in Stockholm was described as "displaying impressive technique" and "shaping the character with mocking good humour".

[7] The same year, she sang Kaja in the premiere of Sven-David Sandström's Staden under Leif Segerstam also at the Royal Opera in Stockholm, where one reviewer commented that "in vocal focus and expression, her full, rich voice is not that far behind Bartoli".

[9] In Brussels in 2000, her Nerone in Handel's Agrippina, alongside Rosemary Joshua's Poppea and Anna Caterina Antonacci's Aggripina was described as "the most convincingly brattish young man imaginable".

[12] In the spring and summer of 2005, Ernman created the title role in Philippe Boesmans's Julie, appearing at la Monnaie, at the Vienna Festival, and in Aix-en-Provence.

[12] In August 2006, Ernman made her debut at the Salzburg Festival as Annio in La clemenza di Tito under conductor Nikolaus Harnoncourt.

Back in the city as Elena in La donna del lago in August 2012, she was "impressive... dealing with the vocal difficulties with aplomb and managing the extra dramatic demands made on her with genuine expressivity".

[18] Also in 2013 she returned to the part of Aggripina at the Gran Teatre del Liceu in Barcelona, in a production by David McVicar conducted by Harry Bicket.

[19] Ernman has sung several major roles with the Staatsoper Berlin, including Cherubino in Le nozze di Figaro and Zerlina in Don Giovanni, both under conductor Daniel Barenboim.

[12] Ernman worked with conductor René Jacobs in the roles of Nerone in Agrippina, Roberto in Scarlatti's Griselda and Diana in Cavalli's La Calisto.

[20] Early recitals on Swedish Radio included Rachmaninov in 1994, The airconditioned nightmare by Olov Olofsson, songs by Gunnar de Frumerie, and an eclectic mix of Fauré, Debussy, Jolivet, Ravel, Bizet, Barber, Ives and Lehrer in 1996, Brahms lieder, and works by Carlid, Mahler and Berio in 1998.

She performed Berio's "Folksongs" with the Stockholm Royal Philharmonic Orchestra under Carlo Rizzi, and at the Verbier Festival with Gustavo Dudamel.

[30] Ernman has been politically active in support of the Paris Agreement; in June 2017 she wrote a collaborative debate piece in Dagens Nyheter.