AbstractType 1 diabetes mellitus is a chronic metabolic condition characterized by the autoimmune damage of pancreatic β cells. As an alternative to continuous exogenous insulin administration of insulin, β cell transplantation is shown to provide an alternative approach for controlling hyperglycemia in diabetes. However, β cell transplantation faces significant challenges of low β cell proliferation and immunologic insults. Thus, novel approaches capable of promoting the islet microenvironment for sustainability is highly desired. This study develops mesenchymal stem cell (MSC)‐laden composite β cell porous microgels (MGs) to address sustainability for the treatment of diabetes. The MGs are prepared via microfluidic droplet templates encapsulating both MSCs and β cells with porogen for creating a porous structure. In addition to offering a suitable microenvironment for nutrient delivery, the porous structure promoted β cell growth and insulin secretion. The outstanding anti‐apoptotic and immunomodulatory roles of MSCs further provide a favorable environment for β cell survival and function. On this basis, the therapeutic performance of the MGs in reducing hyperglycemia and achieving sustained glycemic control in diabetic mice is demonstrated. Collectively, these results show that the novel MGs have great potential for the treatment of diabetes providing a promising platform for clinical β cell transplantation.