He is a Professor of Theoretical Physics at Leiden University (emeritus since July 2021)[1] Van Saarloos has written over 280 papers and has been cited over 12000 times.

He was the chair of the Energy Steering Panel of the European Academies Science Advisory Council (EASAC), of which he serves as president from 2023-2025.

He obtained his doctorate in 1982 in theoretical physics (cum laude) from Leiden University, for his thesis "On nonlinear hydrodynamic fluctuations".

Together with his thesis advisor Mazur, van Saarloos calculated the mobility tensors submerged in viscous fluid of an arbitrary number of spheres in an expansion of power series.

The review van Saarloos wrote on this type of fronts propagation, which occurs in many disciplines in the natural sciences, is his most highly cited paper.

[20] With Varma and Nussinov, van Saarloos reviewed the variety of ways in which Landau Fermi liquids can break down, giving rise to singular behavior.

[22] Van Saarloos was co-editor of the book Dynamical Heterogeneities in Glasses, Colloids, and Granular Media in which he surveyed the theoretical and experimental research that deals with glassy physics[23] and wrote the textbook Soft Matter: concepts, phenomena and applications together with Vitelli and Zeravcic,[24] which is supported by the website softmatterbook.online.