Investigation on adsorption behavior of bovine serum albumin (BSA) on superabsorbent composite is critical for many analytical and biomedical applications. In this study, a novel poly(methacrylic acid)-grafted cellulose/bentonite (PMAA-g-Cell/Bent) superabsorbent composite was synthesized by graft copolymerization reaction of methacrylic acid on cellulose (Cell) in the presence of bentonite (Bent) using N,N′-methylenebisacrylamide as a cross-linker. The original Cell and Bent and composite were analyzed using FTIR, XRD, SEM, TG, and potentiometric titrations. The ability of the composite to adsorb BSA from aqueous solutions has been studied at different optimized conditions. The optimum pH range for the maximum uptake of BSA was 4.5. Maximum adsorption of the BSA, i.e., 99.7%, was achieved from an initial concentration of 10.0 mg/L using 1.0 g composite at pH 4.0. The equilibrium time of adsorbing BSA was about 3 h. Experimental kinetic data were tested with pseudo-first-order and pseudo-second-order kine...