Here an injectable antibacterial aerogel was fabricated with oxidized cellulose nanofiber and chitosan for rapid hemostasis of noncompressible hemorrhage application. Especially, cellulose nanofiber was modified with carboxyl groups by pre-oxidizing in 2,2,6,6-tetramethylpiperidine-1-oxyl combined with high pressure homogenization. Whereafter, the realized carboxyl group of cellulose nanofiber was reacted with the amidogen of chitosan to yield a strong composite aerogel with a nanofiber/nanosheet interlaced structure, which increased the compressive mechanical strength up to 75.4 kPa. In addition, the nanocellulose/chitosan composite aerogel exhibits high water absorption capacity, rapid shape recovery and good antibacterial ability (via Escherichia coli and Staphylococcus aureus). Once absorbing water, the nanocellulose5/chitosan5 compressed aerogel could rapidly recover its shape within 30 s. The in vitro coagulation ability measurement showed that the composite aerogel has a good adhesion and aggregation effect to red blood cells and platelets. Hemolysis and cytotoxicity analysis results indicated a good biocompatibility for the composite aerogel.