<p>Biomass-derived chitin-based nanomaterials are used as fillers to fortify nanocomposites. However, chitin nanowhiskers (ChNWs) exhibit inferior reinforcing ability because of their mediocre modulus values, necessitating focus on other features to boost applicability. In this study, salicylic acid (SA) was grafted onto the surface amino groups (SAGs) of ChNWs and deacetylated ChNWs (DaChNWs) to obtain SA-grafted NWs via condensation amidation. The reaction time and SA/SAG stoichiometric ratio were varied to control the amount of grafted SA, which was quantified by titration of residual SAGs and ultraviolet (UV) absorption measurements of the grafted NWs after dissolution. Under similar conditions, the magnitude of SA grafting (20–167&#xa0;mmol/g_NWs) was greater than that of propionic acid (PA). The ChNWs, DaChNWs, and their SA-grafted counterparts were incorporated into poly(vinyl alcohol) films, realizing nanocomposite films with improved modulus, strength, and UV-shielding performance, enabled by both SA grafting and inherent scattering by the NWs. Soaking cotton fabrics in aqueous SA-grafted-NW suspensions and subsequent drying readily yielded NW-coated fabrics, which exhibited outstanding UV-shielding performance owing to SA grafting, and enabled deodorization of gaseous acetic acid via ionic interaction with residual SAGs. Our findings underscore the utility of SA-grafted (Da) ChNWs as nanofillers/finishes with multiple functionalities (reinforcement, UV shielding, and deodorization).</p> Graphical abstract <p></p>