Powder-based hemostatic technology has offered unprecedented opportunities in surgical sealing and repair of irregularly shaped and noncompressible wounds. Despite their routine use, existing clinical hemostatic powders are challenged either by poor mechanical properties or inadequate adhesion to bleeding tissues in biological environments. Here, inspired by the mussel foot proteins’ fusion assembly strategy, a novel silk fibroin-based hemostatic powder (named as SF/PEG/TA) with instant and robust adhesion performance is developed. Upon absorbing interfacial liquids, the SF/PEG/TA powders rapidly swell into micro-gels and subsequently contact with each other to transform into a macroscopically homogeneous hydrogel in situ, strengthening its interfacial bonding with various substrates in fluidic environments. The in vitro and in vivo results show that the SF/PEG/TA powder possesses ease of use, good biocompatibility, strong antibacterial activities, and effective blood clotting abilities. The superior hemostatic sealing capability of the SF/PEG/TA powder is demonstrated in the rat liver, heart, and gastrointestinal injury models. Moreover, in vivo investigation of rat skin incision and gastrointestinal perforation models validates that the SF/PEG/TA powder promotes wound healing and tissue regeneration. Taken together, compared to existing clinical hemostatic powders, the proposed SF/PEG/TA powder with superior wound treatment capabilities has high potential for clinical hemostasis and emergency rescue.