[1] From 2022 to 2024, Montchalin was the Ambassador and Permanent Representative of France to the Organisation for Economic Co-operation and Development (OECD).

[7] She then studied at the Kennedy School of Government at Harvard University, graduating with a Master of Public Administration in 2014.

From September 2014 she worked at the insurance firm AXA on issues related to global public policy, data protection and climate change.

She has spoken of becoming disenchanted with François Fillon and of being inspired by Emmanuel Macron's reformist and pro-European stance, and also by what she perceives as his willingness to prioritize skills over political experience.

[14][7] On 27 March 2019, Montchalin was appointed as Secretary of State for European Affairs, succeeding Nathalie Loiseau.