After graduating with a degree in Vocal pedagogy in 1998, Lemieux continued with postgraduate studies at the Conservatoire de musique du Québec à Montréal with Marie Daveluy.

[2] She has sung with conductors such as Richard Bradshaw, Franz-Paul Decker, Charles Dutoit, Paul Goodwin, Bernard Labadie, Sir Neville Marriner, Kurt Masur, Marc Minkowski, Kent Nagano, John Nelson, Gianandrea Noseda, Peter Oundjian, Michel Plasson, Federico Maria Sardelli, Michael Schonwandt, Marc Soustrot, Yoav Talmi, Ilan Volkov and Pinchas Zukerman among others.

[citation needed] In 2005, she made her debut with the Staatsoper Berlin, performing in Monteverdi's Il ritorno d'Ulisse in patria under the baton of René Jacobs.

[5] In 2006, Lemieux appeared as Alisa in Donizetti's Lucia di Lammermoor with Opéra de Orange and Anna in Berlioz's Les Troyens with Strasbourg Opera.

[5] In 2008, Lemieux sang the title role in Albert Roussel's Padmavati at the Théâtre du Châtelet, Genevieve in Debussy's Pelléas et Mélisande at the Berlin State Opera, the title role in Handel's Orlando at De Nederlandse Opera, Mistress Quickly in Verdi's Falstaff at the Théâtre des Champs-Élysées, and Marthe in Gounod's Faust at the Opéra de Orange.

[5] In 2009, Lemieux sang Geneviève in Pelléas et Mélisande at the Theater an der Wien, Mistress Quickly at the Bavarian State Opera and the Glyndebourne Festival, and Zita in Gianni Schicchi at the Opéra de Montréal among other engagements.