<h2>Summary</h2> The development and applications of highly efficient and stable catalysts are of vital importance for modern industries varying from chemical production and material transformation to clean energy conversion. Over the last decade, high-index-facet and high-surface-energy nanocrystals have drawn increasing interest in electrocatalysis, photocatalysis, and heterogeneous catalysis, thanks to their excellent catalytic properties. This article provides a comprehensive overview of the up-to-date progress of high-index-facet and high-surface-energy nanocrystals, ranging from a fundamental understanding of the materials and the underpinning science to synthesis and promising applications in catalysis and points out the perspectives for future research and development, in terms of exploring <i>in situ</i> characterization techniques and advanced modeling methodologies, broader materials consideration, including chemical compositions and particle sizes, and various scales of applications.