The formation of Ag nanoparticle/cellulose nanofiber (Ag NP/CNF) composite aerogels were investigated using supercritical CO2 (scCO(2)) drying. CNF hydrogel-ethanol solutions were mixed with Ag NP dispersions in ethylene glycol by ball milling. Subsequently, scCO(2) drying and conventional vacuum drying were evaluated for Ag NP/CNF composite aerogel formation. After scCO(2) drying of the CNF hydrogel solution, a sponge-like CNF aerogel was formed with Ag NPs dispersed in the CNF matrix. In contrast, sheet-like structures and Ag NP agglomerates were obtained by conventional drying. The antifungal and antibacterial activities of the obtained Ag NP/CNF aerogels were evaluated. The composites showed good bacterial (for Escherichia coli) and fungal (for Aspergillus niger) inhibition properties. Furthermore, the effects of drying method and the presence of Ag NPs on the properties of the CNF aerogels, such as surface area, porosity, and antibacterial and antifungal activities, were examined.