Chitosan-catechol, inspired from mussel-adhesive-proteins, is characterized by the formation of an adhesive membrane complex through instant bonding with serum proteins not found in chitosan. Using this intrinsic property, chitosan-catechol is widely applied for hemostatic needles, general hemostatic materials, nanoparticle composites, and 3D printing. Despite its versatility, the practical use of chitosan-catechol in the clinic is limited due to its undesired immune responses. Herein, a catechol-conjugated glycol chitosan is proposed as an alternative hemostatic hydrogel with negligible immune responses enabling the replacement of chitosan-catechol. Comparative cellular toxicity and in vivo skin irritation between chitosan-catechol and glycol chitosan-catechol are evaluated. Their immune responses are also assessed using histological analysis after subcutaneous implantation into mice. The results show that glycol chitosan-catechol significantly attenuates the immune response compared with chitosan-catechol; this finding is likely due to the antibiofouling effect of ethylene glycol groups and the reduced adhesion of immune cells. Finally, the tissue adhesion and hemostatic ability of glycol chitosan-catechol hydrogels reveal that these ethylene glycol groups do not dramatically modify the adhesiveness and hemostatic ability compared with nonglycol chitosan-catechol. This study suggests that glycol chitosan-catechol can be a promising alternative to chitosan-catechol in various biomedical fields such as hemostatic agents.