Upon graduating, Des Cars joined the Institut national du patrimoine and took her first position as curator at the Musée d'Orsay in 1994.
She is the author of numerous illustrated essays, including a book on Pre-Raphaelites for the collection 'Découvertes Gallimard', Les Préraphaélites : Un modernisme à l'anglaise.
Des Cars was appointed scientific director of the Agence France-Muséums [fr] in July 2007, French operator in charge of the development of the Louvre Abu Dhabi.
She was also promoted to general curator of heritage in 2011 and was appointed director of the Musée de l'Orangerie in January 2014, by the Minister of Culture, Aurélie Filippetti.
[1][8] Des Cars was appointed to assume the role of Director of the Louvre Museum from 1 September 2021, becoming the first woman to hold the position in the establishment's 228-year history.