Objective: One of the leading causes of death following traumatic injury is exsanguination. Biological material-based hemostatic agents such as fibrin, thrombin, and albumin have a high risk for causing infection. Synthetic peptide-based hemostatic agents offer an attractive alternative. The objective of this study is to explore the potential of h9e peptide as an effective hemostatic agent in both in vitro and in vivo models. Approach: In vitro blood coagulation kinetics in the presence of h9e peptide was determined as a function of gelation time using a dynamic rheometer. In vivo hemostatic effects were studied using the Wistar rat model. Results were compared to those of the commercial hemostatic product Celox™, a chitosan-based product. Adhesion of h9e peptide was evaluated using the platelet adhesion test. Biocompatibility of h9e peptide was studied in vivo using a mouse model. Results: After h9e peptide solution was mixed with blood, gelation started immediately, increased rapidly with time, and reached more than 100 Pa within 3 s. Blood coagulation strength increased as h9e peptide wt% concentration increased. In the rat model, h9e peptide solution at 5% weight concentration significantly reduced both bleeding time and blood loss, outperforming Celox. Preliminary pathological studies indicate that h9e peptide solution is biocompatible and did not have negative effects when injected subcutaneously in a mouse model. Innovation: For the first time, h9e peptide was found to have highly efficient hemostatic effects by forming nanoweb-like structures, which act as a preliminary thrombus and a surface to arrest bleeding 82% faster compared to the commercial hemostatic agent Celox. Conclusion: This study demonstrates that h9e peptide is a promising hemostatic biomaterial, not only because of its greater hemostatic effect than commercial product Celox but also because of its excellent biocompatibility based on the in vivo mouse model study.