This perspective gives an overview of recent progress in thefield of photocured polymer composites based on variousforms of nanocelluloses, with a focus on cellulose nanofibrils. The manufacturing processes and performances of these nanocellulosecomposites are detailed, comprising solvent-assisted mixing processes, emulsification, coating and casting processes, preformimpregnation, and 3D printing. Attention is also paid to life-cycle engineered approaches to improve their sustainability. Thesematerialsfind applications in numerous domains, primarily as protective coatings but also as diffusion barrier composites andfilmsfor packaging and encapsulation of electronics, as composite hydrogels for biomedical applications, and as membranes for battery technologies.