Mariana graduated as a lawyer at the University of Chile. She has worked for over seven years at the Office of the National Prosecutor for Economic Affairs and prior to that in private practice. She was Chief of the Cabinet of former Minister of Energy (2007-2010), Marcelo Tokman, and was subsequently appointed in 2010 by former President Michelle Bachelet, the first female undersecretary of energy in the history of Chile. When the government ended, she became Vice-President of Corporate Affairs for AES Gener and is responsible for the areas of Corporate Social Responsibility, Communications, Institutional Affairs and the AES Gener Foundation. In addition, she served as Social Manager for Alto Maipo.

Before returning to AES Chile, she held the position of Vice President of Sustainability and Corporate Affairs at WOM for three years.