Wound healing, especially for diabetic wounds, is a lengthy and complicated process involving interactions and responses at the protein, cell, and tissue levels. Loading of growth factors into a hydrogel to construct a sustained‐release system is considered a promising approach to improve wound healing. The present study investigates the effect of thermosensitive heparin‐poloxamer (HP) hydrogel–encapsulated recombinant human fibroblast growth factor 21 (rhFGF21) on wound healing in mice with streptozotocin‐induced diabetes mellitus. First, we studied the in vitro release of rhFGF21 from the rhFGF21‐HP coacervate. The results showed that HP might control the release of rhFGF21. Next, we examined the effect of rhFGF21‐HP on skin wound healing in diabetic mice. Our data showed that rhFGF21‐HP significantly improved wound closure; promoted granulation, collagen deposition, and re‐epithelialization; and enhanced the expression of CD31. Moreover, rhFGF21‐HP had obvious advantages in diabetic wound healing. Therefore, the results suggest that the rhFGF21‐HP hydrogel polymer plays an important role in skin wound healing. This work provides a suitable sustained‐release delivery system that can continuously release rhFGF21 and presents a promising therapeutic strategy for wound healing in patients with diabetes.—Liu, H., Zhao, Y., Zou, Y., Huang, W., Zhu, L., Liu, F., Wang, D., Guo, K., Hu, J., Chen, J., Ye, L., Li, X., Lin, L. Heparin‐poloxamer hydrogel–encapsulated rhFGF21 enhances wound healing in diabetic mice. FASEB J. 33, 9858–9870 (2019). http://www.fasebj.org