Born in Bistrița,[2] Hartig studied at the Gheorghe Dima Music Academy in Cluj-Napoca, graduating in 2006.
In 2012, London's The Daily Telegraph reported that she was "enjoying special success" as Mimì.
[3] On 1 November 2014, Hartig made her Metropolitan Opera Live in HD debut as Micaëla in Carmen.
Following the cancellation of Ailyn Pérez, Hartig made her debut at the Gran Teatre del Liceu, Barcelona in July 2015 as Violetta in La traviata .
[4] On 30 January 2016, she sang Liù from Turandot in another Metropolitan Opera Live in HD performance alongside Nina Stemme in the title role, Marco Berti [Wikidata] as Calaf and Alexander Tsymbalyuk as Timur.