Marnix joined Philips’ legal department in 2007 and became head of Group Legal in 2010. In this role he was responsible for the various Group Legal departments, including Corporate & Financial Law, Legal Compliance and Legal M&A. In 2014, Marnix became Chief Legal Officer of Royal Philips and Member of the Executive Committee. In November 2017, he was appointed Member of the Philips Board of Management.
Before joining Philips, Marnix worked as an in-house lawyer for Akzo Nobel and before that as an attorney in a private practice. Since 2011, he is a part-time Professor of International Corporate Governance at the Erasmus School of Law in Rotterdam.