The development of nanocellulose and nanocellulose-based composites and materials has attracted significant interest in recent decades because they show unique and potentially useful features, including abundance, renewability, high strength and stiffness, eco-friendliness, and low weight. This review addresses critical factors in the manufacturing of nanocellulose composites, followed by introducing and comprehensively discussing various nanocellulose composite processing techniques. The review also provides advances on rubber and thermoset polymer matrices, such as unsaturated polyester resin, formaldehyde resins, and polyethylene terephthalate, used to reinforce cellulose nanocrystals (CNCs) or cellulose nanofibers (CNFs). The paper concludes with new findings and cutting-edge studies on electrospun nanocellulose composites. Different aspects, including preparation methods, morphology, mechanical behavior, thermal properties, and barrier action, as well as comparisons of CNC- and CNF-reinforced rubbers or thermoset polymers and electrospun composites, are investigated. (C) 2017 Elsevier Ltd. All rights reserved.