Polysaccharides have attracted considerable attention in a broad range of applications in recent years, which is due to their remarkable features such as biocompatibility, biodegradability, renewable origin, and facile modification. Considerable research efforts have been focused on developing polysaccharide nanoparticles and to promote their applications in various areas and biomedicine in particular. The present review highlights the properties of common polysaccharides used in nanoparticle formation as well as strategies to fabricate polysaccharide nanoparticles. Furthermore, the combination of polysaccharide nanoparticles and polymers is presented and brought into the context of applications. Finally, applications of polysaccharide nanoparticles as nano-delivery system, Pickering emulsion stabilisers, and material reinforcing agent in the fields of nanomedicine, cosmetics, and food system are highlighted. Moreover, this review describes and critically discusses present limitations and drawbacks in the preparation and use of polysaccharide nanoparticles, revealing directions to develop polysaccharide nanoparticles for further utilisation in various applications in the future.