Process systems engineering (PSE), as the name suggests, emphasizes an approach to understanding the behavior of systems as a whole with a view to improving decision-making for optimization and control of processes. The discipline emphasizes the application of mathematical techniques in this effort, and a plausible claim has been made that is at the very core of the discipline of chemical engineering. Being a generalized approach to process systems in general, it finds wide application to many areas in chemical engineering. This work reviews the application of PSE to the area of reaction engineering, which is also at the core of chemical engineering. We highlight the impactful applications of PSE in reaction engineering and discuss aspects of model building and analysis, reactor control, optimization, chemometrics, and chemoinformatics.