An N-halamine precursor monomer, cyanuric chloride (CYCH), was attached onto nanocrystalline cellulose (NCC) and chloropropyltriethoxysilane (CPTES) was used as a crosslinking agent to prepare hydrogels based on the modified nanocrystalline cellulose. The aerogels were obtained by freeze-drying the hydrogels followed by chlorination. Microscopic investigation of the morphology revealed that the aerogels were porous with three-dimensional web-like microstructure. Their hydrophobic properties were efficient in removing dodecane spills from water. The response of the chlorinated aerogels challenged against Staphylococcus aureus (ATCC 6538) and Escherichia coli O157:H7 (ATCC 43895) showed their potent antimicrobial activities in killing these two bacterial species. Their properties of being ultralight, highly porous, hydrophobic, reusable, superabsorbing, and antibacterial efficient render these aerogels promising materials for cleaning up oil spills and inactivating bacteria.