Martijn obtained his PhD in Applied Economics from KU Leuven in 2018. His dissertation was titled "Institutional Choice and the Political Economy of Federalism and European Integration".

In April 2022, Martijn was a Visiting Fellow at LUISS university Rome. He spent Spring Quarter 2015 at Stanford University for research, and Fall 2009 at the University of Pennsylvania on an undergraduate exchange at the Wharton School of Business.

Prior to starting his PhD, he worked as a management consultant at the Boston Consulting Group (2012-2014).