Gelatin (GE), a nontoxic and degradable biomass resource, is a multistage hydrolysate of collagen. However, its application in adhesives was always limited by its brittleness and poor water resistance. In order to overcome this shortcoming, herein, epoxy-terminated hyperbranched polymers (EHPAEs) were first selected as a cross-linking agent to modify the GE extracted from leather solid wastes to prepare a series of novel GE-based environmentally friendly adhesives. First, EHPAE was synthesized and the structure of the hyperbranched polymer was measured by Fourier-transform infrared and H-1 NMR spectroscopy. Then, the adhesives were obtained using the EHPAE to modify GE. The adhesion effect of the prepared adhesives was evaluated by tensile and T-peel tests on the surface of leather, in order to determine whether this adhesive achieved the quality requirements for footwear and bags. The result indicated that EHPAE-modified GE-based adhesives had higher solid content, superior adhesion ability, and water resistance. Moreover, the bonding layer of this adhesive was tough and ductile, while the bonding layers of the recently reported GE-based adhesives were brittle. This adhesive also surpassed the recently reported GE-based adhesives in terms of water resistance and adhesion performance.