Anastomotic leakage and tissue adhesion are significant complications associated with colorectal surgeries, such as the resection of colorectal cancer. However, an effective biomedical apparatus has yet to be developed to address both complications. In the present study, we developed a tissue-sealing, anti-adhesive hydrogel composed of decyl group-modified gelatin (C10-ApGltn) and a poly (ethylene glycol)-based crosslinker. C10-ApGltn based hydrogel (C10-gel) demonstrated increased elastic modulus and suppressed swelling ratio compared with the unmodified ApGltn. Furthermore, C10-gel effectively sealed a water leakage model of intestine tissue and prevented contact between two intestinal tissue samples. In vivo experiments revealed that C10-gel degraded almost entirely in 28 days and prevented cell infiltration for 14 days, which effectively inhibits tissue adhesion. Therefore, C10-gel is a biocompatible hydrogel that can be used to mitigate or prevent anastomotic leakage and prevent tissue adhesion in colorectal surgery.