A native of Saint-Symphorien-sur-Coise, Gassilloud studied at Lumière University Lyon 2 and Emlyon Business School.

He succeeded Françoise Dumas who lost her seat in the 2022 legislative election.

[4] He also served in the Parliamentary Office for the Evaluation of Scientific and Technological Choices (OPECST) from 2017 to 2022.

[5] In addition to his committee assignments, Gassilloud is part of a number of parliamentary friendship groups, including with the Central African Republic, Chad and Mali.

[4] He served in the Assemblée parlementaire de la Francophonie (APF) from 2017 to 2022, before he was part of the French delegation to the NATO Parliamentary Assembly from 2022 to 2024, where he served on the Political Committee, the Subcommittee on NATO Partnerships, as well as the Subcommittee on Transatlantic Relations.