This paper presents a novel polyurethane underwater adhesive (PUWA) inspired by mussels, designed for biomedical applications. The PUWA is developed through an injectable two-component curing process involving a biocompatible polyurethane prepolymer (component A) and dopamine-modified lysine derivatives (component B). This adhesive exhibits rapid and strong underwater bonding, with impressive bonding strength of 40 kPa on pork skin and excellent burst pressure of 394 mmHg. It demonstrates robust adhesion in hostile environments, including acid, alkali, and saline solutions. The PUWA also shows good biocompatibility and hemostatic properties, effectively sealing wounds and promoting healing. The rapid curing and simple application of the PUWA make it a promising candidate for both biomedical and industrial applications.This paper presents a novel polyurethane underwater adhesive (PUWA) inspired by mussels, designed for biomedical applications. The PUWA is developed through an injectable two-component curing process involving a biocompatible polyurethane prepolymer (component A) and dopamine-modified lysine derivatives (component B). This adhesive exhibits rapid and strong underwater bonding, with impressive bonding strength of 40 kPa on pork skin and excellent burst pressure of 394 mmHg. It demonstrates robust adhesion in hostile environments, including acid, alkali, and saline solutions. The PUWA also shows good biocompatibility and hemostatic properties, effectively sealing wounds and promoting healing. The rapid curing and simple application of the PUWA make it a promising candidate for both biomedical and industrial applications.