On May 14, 2018, Marinus van IJzendoorn celebrated his 66th birthday which unfortunately also was the obligatory retirement age in the Netherlands for his age cohort. He became an emeritus professor at Leiden University where he remains involved in several research programs, among others the Leiden Consortium for Individual Development (L-CID as Scientific Consultant), 3G Family Lab, and Father Trials (cooperating with Marian Bakermans-Kranenburg who is now a professor at ISPA in Lisbon, Portugal.

At Erasmus University Rotterdam he was a professor of human development in the Department of Psychology, Education, and Child Studies (DPECS) for 1 day per week until May 2022, and a visiting professor in the same department until May 2023. He was one of the co-leaders of Generation R (Erasmus Medical Center). He is an emeritus professor of Erasmus University Rotterdam.

From 2017 to 2020 he was a Honorary Senior Visiting Fellow, Department of Public Health and Primary Care, School of Clinical Medicine, University of Cambridge, UK, and he was in 2019 Visiting Fellow at Sidney Sussex College, working in the Applied Social Sciences Group headed by Robbie Duschinsky.

From 2018 to 2022 he was a visiting professor of human development at the School of Psychology, Capital Normal University, Beijing, China. He was teaching courses for faculty, MA and PhD students on meta-analysis of human development research and on child socio-emotional development, and served as a scientific advisor for child development research.

In October 2022 he was Visiting Professor at the Department of Psychology and Cognitive Science of the University of Trento, Italy.

In December 2020 he was invited to be a visiting professor in the Research Department of Clinical, Educational and Health Psychology, Division on Psychology and Language Sciences, Faculty of Brain Sciences, UCL,  London, UK. 

At Monash University in Melbourne, Australia, he is an adjunct professor at the Department of Psychiatry, since March 2023, to work with professor Megan Galbally and her team on the MPEWS longitudinal study.