Today, we are facing an unprecedented challenge to produce enough protein to feed the growing population in a way that is environmentally sustainable, easily accessible, and affordable while also meeting changing dietary preferences. Plant proteins are gaining attention because of their superiority in these regards. However, their relatively lower nutritional quality and functionality limit their use in the food industry. Progress has been made in exploring new plant protein sources, processing innovation, functionality modifications, and diversifying applications thanks to the efforts from both academia and industry. This chapter summarizes the nutritional composition and protein class distribution in popular plant protein sources. We also highlight the advantages and disadvantages of various production and modification techniques. Finally, we briefly introduce the application of plant proteins in end-products, with further discussion of meat analogues, a popular application. Overall, plant proteins have exhibited a great potential as alternative protein sources, but more research is needed to address the challenges in flavor, color, functionality, and nutrition of plant protein-based products to satisfy consumers.