New collaborative paper published in Macromolecular Rapid Communications. In this study, we demonstrate a particle-templating strategy to create hierarchically porous, chemically functional coatings on cellulose fibers. Silica-polymer core-shell particles are deposited on cellulose paper and subsequently etched to generate porous polymer coatings with tunable surface chemistry, including hydroxy and epoxy groups. This approach opens new opportunities for smart cellulose-based filtration systems, paper-based sensors, and functional adsorbers.