Fillers are added during the papermaking process in order to produce paper, paperboard, and packaging materials with enhanced properties. Fillers act as a binder to closely entangle paper fibers together in order to form finished paper. These fillers account for physical characteristics such as opacity, gloss, finish, and brightness in various grades of paper. Varieties of fillers such as ground limestone, ground chalk, clay, talc, precipitated calcium carbonate (PCC), titanium dioxide (TiO2), gypsum, carbohydrate-based fillers, starch-based fillers, cellulose-based fillers, hemicellulose-based fillers, and nanofillers are used in pulp and paper industry. Among these nanofillers have gained tremendous attention for paper production because these results into elevated mechanical and physical properties in paper, effective utilization of raw material for pulping, and also contributes towards the economy of paper industry. Utilization of nanofiller in paper industry is advantageous in terms of barrier properties, enhanced printability, and improved strength, durability, and production of lightweight sustainable packaging. Nanocellulose, nanoclays, nanotitania, carbon nanotubes, nanocalcium carbonate, nanocalcium silicate, nano kaoline, nano ZnO/hybrid, and nano zeolites are some of the examples of nanofillers being utilized in papermaking process. This chapter briefly discusses types, production techniques, and properties of various nanofillers used for paper production. The different types of nanofillers and their benefits in papermaking process have also been presented. Various techniques such as SEM, XRD, TGA, FTIR, DSC, etc. applied for characterization of nanofillers reported in the literature have also been incorporated in the chapter. The chapter also briefs about the various challenges pertaining to usage of nanofillers in the paper industry. This chapter will help the pulp and paper professionals to select appropriate end product–specific nanofillers for production of wide range of paper-based products.