After studying politics at Science PO and then at the ENA, Marie Masmonteil worked at Télé-Images and then Productions Lazennec (TV production companies). She also spent a year working as a consultant with the CNC (Centre National de la Cinématographie) followed by a 6 month experience as a technical consultant at the French Ministry of Culture for Mme la Ministe Catherine Tasca's cabinet in 1991, where she was able to expand her knowledge in administrative management of the audiovisual sector.
She then created the Capa Drama company which she manages for 3 years. During this time she launched the film collection "Combats de Femmes" broadcasted on M6 (six TV movies written and directed by young directors such as Eric Woreth, Pascale Bailly, Laurent Dussaux et Laurent Jaoui) and produced two important TV films with Canal+ ("Facteur VIII" directed by Alain Tasma on the subject of blood contamination by the HIV, "Si je t'oublie Sarajevo" directed by Arnaud Selignac on the Bosnian war).
Marie was vice-resident of the Premier Collège d'avance sur recettes (public funding body for feature films) from January 2006 to December 2008.
Marie Masmonteil was President of the SPI (Syndicat des Producteurs Indépendants, the independent producers' union) from March 2001 until march 2005, then became president of the Cinema body of the SPI. In March 2009, she was once again elected President.