Abstract Controlling bleeding by applying pressing cotton gauze is the most facile treatment in prehospital emergencies. However, the wettable nature of cotton fibers leads to unnecessary blood loss due to excessive blood absorption, inseparable adhesion‐induced pain, and pliable to infection. Here, a kind of ultra‐hydrophobic haemostatic anti‐adhesive gauze whose surface is loaded with polydimethylsiloxane (PDMS) and hydrophobic‐modified cellulose nanocrystals (CNCs), achieving a water contact angle of ≈160° is developed. It is demonstrated that the mechanism by which hydrophobic CNCs promote blood clotting is associated with their ability to activate coagulation factors, contributing to fibrin formation, and promoting platelet activation. The blood‐restricting effect results from the low surface energy layer formed by PDMS and then the alkyl chains of hydrophobic CNCs are combined. The produced ultra‐hydrophobic gauze resists blood flow and diffusion, decreases blood loss, is effortlessly peelable, and minimizes pathogen adhesion. Compared to the commercial cotton gauze, this gauze achieved effective haemostasis and antiadhesion by reducing blood loss by more than 90%, shortening haemostasis time by more than 75%, lowering peeling force by more than 90% and minifying bacterium attachment by more than 95%. This work presents promising applications in terms of prehospital first aid.