Various bioadhesives have been used as a wound closure, a hemostatic agent, a tissue sealant and other medical applications. Among them, mussel-inspired adhesives have been widely studied as they have shown strong tissue adhesiveness even in wet conditions. It is demonstrated that molecular oxygen (O2) is an essential signaling molecule in the wound healing and tissue regeneration. Herein, we developed an oxygen-generating gelatin-based adhesive formed via calcium peroxide-mediated crosslinking and in situ polymerization of dopamine. We demonstrate that the hydrogels rapidly generate O2 up to 70% pO2 and release O2 from hydrogels for 7 days in vitro. The hydrogels exhibit controllable tissue adhesive strength (15−38 kPa) and enhance wound healing with neovascularization in mouse skin. These results suggest that our hydrogel holds a great potential as tissue adhesives for wound management as well as tissue regenerative materials.