She has collaborated with conductors including Yves Abel, Gary Bertini, Christoph Eschenbach, Jane Glover, Neemi Järvi, Fabio Luisi, Marc Minkowski, Kirill Petrenko, Markus Poschner and Ulf Schirmer.
Mills has repeated Mimì in Berlin, Detroit, Santiago de Chile, Antwerp (Belgium), Strasbourg, Geneva, and San Francisco.
At the San Francisco Opera, she made her debut as an Adler Fellow[1] as the 15-year-old Girl in Lulu and created the role of Cecile de Volanges for their production of the world premiere of The Dangerous Liaisons.
The artist made her debut at the Paris Bastille in 1997 in the title role of Massenet's Manon, and was re-engaged in the same theatre to sing Micaela in Carmen as well as Marguerite in Faust and at the Palais Garnier as the Infantin in Zemlimsky's Der Zwerg.
Mills sang her first Katya Kabanova at Theatre Saint Gallen, Switzerland to acclaim in 2004 and could also be heard that same year at the Theater an der Wien as Jitka in Smetana’s Dalibor.
[2] Mills originated the title role of Joan of Arc in Walter Braunfels' new opera Szenen aus dem Leben der Heiligen Johanna in a Christoph Schlingensief production at the Deutsche Oper in Berlin in 2008,[3] which repeated in 2010[4] and 2012.