Hydrogel bioadhesives have emerged as one of the most promising alternatives to sutures and staples for wound sealing and repairing, owing to their unique advantages in biocompatibility, mechanical compliance and minimally invasive manipulation. However, only a few hydrogel bioadhesives have been successfully used for gastric perforation repairing, due to their undesirable swelling when in direct contacting with extremely acidic gastric fluids, thereby accompanying with a graduallydeteriorated adhesion performance. Herein, we develop an acid-tolerant hydrogels (ATGels) bioadhesive, which integrates two distinct components, an acid-tolerant hydrogel substrate and an adhesive polymer brush layer. The ATGels bioadhesive could form instant, atraumatic, fluid-tight and sutureless sealing of gastric perforation, and enable robust biointerfaces in direct contact with gastric fluids, addressing the key limitations with sutures and commercially-available tissue adhesives. Moreover, in vivo investigation on gastric perforation of rat model validates the proposed acid-tolerant bioadhesion, and identifies the mechanisms for accelerated gastric perforation repairing through alleviated inflammation, which suppressed fibrosis and enhanced angiogenesis.