Our society is facing serious challenges in terms of energy demands, availability of resources, climate change, and water supply, which are closely related to our daily lives in the 21st century. Nanocatalysis is capable of improving sustainability by minimizing energy and feedstock requirements. In this chapter, various types of nanocatalysts based on different key components are reviewed, including metallic nanoparticles, magnetically recyclable nanocatalysts, nanocarbon materials, and nanostructured porous materials. Furthermore, the applications of these nanocatalysts in several sustainable domains, including photocatalysis, environmental remediation, and the production of high-value fuels and chemicals, are further summarized. The challenges and further endeavors with nanocatalysts are finally proposed.