During this time, he graduated from the École Centrale Paris through an exchange program in 2009, and earned a master's degree in fundamental physics from the Paris-Sud University the following year.

[1] His thesis was written on "Dynamical modelling from resting-state brain imaging" under supervision of professors Rodolphe Sepulchre and Steven Laureys.

He worked on models of brain function as a post-doctoral research fellow at the École Polytechnique Fédérale de Lausanne in Switzerland from 2018 to 2021.

[1][11] Starting in 2021, he has held the permanent position of Research and Teaching Fellow at the University of Geneva and the École Polytechnique Fédérale de Lausanne.

[13][14] Liégeois completed ESA's Basic Training curriculum at the European Astronaut Centre, and graduated alongside his classmates from "The Hoppers"[15] group on the 22nd of April 2024.

[21] After he completed his post-doctoral research in Singapore in 2017, he and his spouse took four months to return to Belgium by bike, meeting with poets in twelve countries throughout Asia and Europe on the way.