[12] In spring 2010, before completing her studies, Giunta made her professional debut as Cherubino in Le nozze di Figaro with Opera Atelier and the Tafelmusik Baroque Orchestra in Toronto.

She spent summer 2010 at the Ravinia Festival in Chicago, where she was invited to audition for the Metropolitan Opera Lindemann Young Artist Development Program, which she joined in September 2011.

Earlier in 2011, she had made her American operatic debut as Pribaoutki in the acclaimed Robert Lepage production of Stravinsky's The Nightingale & Other Short Fables, on tour with the Canadian Opera Company.

[13] In 2012, she performed in two Metropolitan Opera Young Artist productions, as Phénice in Gluck's Armide, and as Dorabella in Stephen Wadsworth's staging of Così fan tutte.

[13] In 2013 she returned to the Canadian Opera Company singing both Sesto and Annio in Mozart's La clemenza di Tito, directed by Christopher Alden.

In early 2015, Giunta returned to the Metropolitan Opera as Olga in a new production of Lehár's The Merry Widow, broadcast worldwide for their Live in HD series.

[13] In 2017, she starred in three productions for Opera North, singing the title roles in La Cenerentola and L'enfant et les sortilèges, as well as Dinah in Bernstein's Trouble in Tahiti, again to critical acclaim.

In 2020, before COVID-19 pandemic-related cancellations, Giunta also debuted at the Deutsche Oper am Rhein as Bradamante in Handel's Alcina, and reprised the role of Dodo in Breaking the Waves for the Adelaide Festival.