We present here a straightforward strategy to prepare multifunctional cellulose by a one-pot modified carboxymethylation reaction. We focused on the introduction of negative charge (carboxymethyl groups) and benzophenone moieties {[4(bromomethyl)phenyl][4-(prop-2-yn-1-yloxy)phenyl]methanone} on the surface of cellulose fibers by a concomitant Williamson's etherification. The presence of negative charge on the cellulose surface facilitated fibrillation, and we obtained microfibrillated cellulose by soft magnetic stirring. The chemical grafting of benzophenone functionalities was evidenced by combining Fourier transform infrared and solid-state 13C CP/MAS NMR techniques and by the polymerization of different monomers (methyl methacrylate, dodecyl methacrylate, and styrene) on the cellulose surface. The presence of both functionalities allowed fabricating papers and 3D networks, and their subsequent cross-linking by the carboxylate groups, and hydrophobization by polymerization at the benzophenone groups. Indeed, bifunctional cellulose showed interesting properties that were not achieved by the mixture of monofunctional celluloses.