Current hyaluronic acid (HA) hydrogel systems often cause cytotoxicity to encapsulated cells and lack the adhesive property required for effective localization of transplanted cells in vivo. In addition, the injection of hydrogel into certain organs (e.g., liver, heart) induces tissue damage and hemorrhage. In this study, we describe a bioinspired, tissue-adhesive hydrogel that overcomes the limitations of current HA hydrogels through its improved biocompatibility and potential for minimally invasive cell transplantation. HA functionalized with an adhesive catecholamine motif of mussel foot protein forms HA-catechol (HA-CA) hydrogel via oxidative crosslinking. HA-CA hydrogel increases viability, reduces apoptosis, and enhances the function of two types of cells (human adipose-derived stem cells and hepatocytes) compared with a typical HA hydrogel crosslinked by photopolymerization. Due to the strong tissue adhesiveness of the HA-CA hydrogel, cells are easily and efficiently transplanted onto various tissues (e.g., liver and heart) without the need for injection. Stem cell therapy using the HA-CA hydrogel increases angiogenesis in vivo, leading to improved treatment of ischemic diseases. HA-CA hydrogel also improved hepatic functions of transplanted hepatocytes in vivo. Thus, this bioinspired, tissue-adhesive HA hydrogel can enhance the efficacy of minimally invasive cell therapy.