The intraperitoneal (IP) cavity is the largest fluid-filled space in the body and contains important organs. Although peritoneal fluid from the abdominal cavity lubricates and allows organ motion, this fluid also effectively prevents polymeric material implantation. Anastomotic leakage after surgery has been reported but few sealing methods have been developed. Herein, a fluid-resistant adhesive called IP patch is reported that seals intestinal neo-anastomosis sites, preventing anastomotic leakage after colorectal surgery. The bursting pressure, which is the most important index of the degree of healing after colorectal anastomosis surgery, is measured from an IP patch applied to rats (188.3 +/- 14.5 mmHg) and is highly similar to the pressure observed from normal tissue (210.2 +/- 22.9 mmHg). Additionally, IP patches can act as unprecedented local drug reservoirs due to the aforementioned tissue adhesive property. Drug-loaded IP patches successfully treated multiple-site occurrence of small peritoneal cancerous colonies. The anticancer drug-loaded IP patches are applied to potential risk regions for recurrent and metastasized cancer in the IP cavity after the resection of peritoneal solid tumors. Thus, the multifunctionality of IP patches can be usefully exploited as an adhesive biomaterial that works effectively in difficult-to-treat diseases observed in IP environments.