Thomas is an Associate Professor at Victoria University of Wellington. Before that he was an Assistant Professor at the Technische Universität Darmstadt (Germany) and an Acting Professor at the Software Engineering Department of the University of Mannheim (Germany).

Thomas received a Ten-Year Most Influential Regular Paper award from the Springer journal Software and Systems Modeling. He received three Best Reviewer awards from the same journal. He furthermore received two ACM SIGSOFT Distinguished Paper awards. Thomas was the General Chair of the ACM/IEEE conference MODELS 2011 and a Programme Committee Co-Chair of the ACM/IEEE conference MODELS 2023.