AbstractMost of the current bioadhesives cannot perform well on bleeding tissues while postoperative adhesion is a general but serious clinical issue. Here, a three‐layer biodegradable Janus tissue patch (J‐TP) that is able to simultaneously enable efficient closure of bleeding wounds with significantly promoted clotting ability and suppressed postoperative adhesion of tissues is reported. A dry adhesive hydrogel bottom layer of the J‐TP can form rapid (within 15 s) and strong (tensile strength up to 98 kPa) adhesion to bleeding/wet tissues with high bursting pressure (about 312.5 mmHg on a sealed porcine skin) through hydrogen binding and covalent conjugation between the carboxyl & N‐hydroxy succinimide (NHS) groups of hydrogel and the primary amine groups of tissues, while the phosphonic motifs can significantly reduce blood loss (by 81% on a rat bleeding liver model) of bleeding wounds. A thin polylactic acid (PLA) middle layer can improve the tensile strength (by 132%) of the J‐TP in wet conditions while the grafted zwitterionic polymers can effectively prevent postoperative tissue adhesion and inflammatory reaction. This J‐TP may be a promising tissue patch to assist the clinical treatment of injured bleeding tissues with inhibited postoperative adhesion.