Pressure ulcers (PUs) are common skin injuries known for their high morbidity, rapid onset, susceptibility to infection, and challenging healing process. One potential therapy for PUs is cell-based therapy using mesenchymal stem cells (MSCs). However, poor survival and low cell retention of MSCs on skin lesions limit their therapeutic effects and applications. In this study, we prepared an extracellular matrix (dECM) hydrogel decellularized from the human umbilical cord (UC). A patch composed of UC-dECM and UC-MSCs was employed in the treatment of PUs in C57BL/6 mice. Our results indicate that the UC-dECM hydrogel effectively sustains cell viability, enhances the stemness-related gene expression in UC-MSCs, and promotes human umbilical vein endothelial cells (HUVECs) migration and angiogenesis. Compared to the groups treated with the patch containing only UC-dECM, injection of UC-MSCs or gauze dressing, the patch combining UC-dECM hydrogel with UC-MSCs significantly accelerated PU healing. This positive outcome can be attributed to the promotion of tissue re-epithelialization, collagen deposition, angiogenesis, and inflammation inhibition. Our results suggest that the composite patch, comprised of UC-dECM hydrogel and UC-MSCs, may be a promising therapeutic approach for PU treatment.