A former director of the cabinet of Pierre Moscovici, then of Emmanuel Macron at the Ministry of Finance, he was appointed secretary general of the Élysée Palace on 14 May 2017.

[4] Kohler began his career at the Direction générale du Trésor of the French Ministry for the Economy and Finance, then he was detached to various organisations, including the International Monetary Fund, then the Agence des participations de l'État.

[3][6] When Macron resigned in 2016 to establish En marche !, Kohler returned to a position in the private sector as chief financial officer of MSC Cruises.

[7] At the request of his employer, he settled in Grenoble and then Geneva, but continued to work remotely for Macron by mail and WhatsApp loops.

[12][13] In 2022, anti-graft group Anticor filed a complaint accusing Kohler of breaking conflict-of-interest rules after it emerged he had family links to the Italian owners of MSC Cruises.