Dural sealants are widely used in neurosurgery for rapid application and watertight closure. However, conventional glue-type adhesives suffer from uncontrolled flow and nonspecific adhesion to surrounding tissues. Here, we developed a monolithic Janus dural patch from photocurable hyaluronic acid that enables strong tissue adhesion and a lubricating surface after brief exposure to non-toxic visible light (405 nm, 5 s, < 1 J cm⁻²). Janus functionality was introduced through an asymmetric porous structure formed by lyophilization. The HA photopatch demonstrated high burst pressure resistance (up to 208.5 mmHg, ~10× normal intracranial pressure) and reduced friction by 50%. The Janus HA photopatch also showed strong wet adhesion, limited swelling (< 200%), and prevented penetration into brain tissue. In a rabbit durotomy model, the HA photopatch achieved rapid and effective dural sealing without pathological changes. These results highlight its potential for reliable clinical watertight sealing.