The dysregulated immune microenvironment of diabetic wounds, characterized by aberrant immune cell infiltration, persistent cytokine production, accumulation of metabolic by-products, and elevated oxidative stress, presents substantial clinical challenges to effective wound healing. Microneedles, through the formation of reversible microchannels that enable efficient transdermal drug delivery, offer a promising strategy for immunomodulation and tissue repair. This review comprehensively summarizes recent advances in immunomodulatory microneedles for diabetic wound healing. We discuss key designs and engineering parameters, with a focus on how material composition and structural tuning influence immune responses. Special attention is given to diverse therapeutic modalities delivered via microneedles, including small molecules, proteins, nucleic acids, cells, exosomes, inorganic agents, gaseous therapeutics, and integrated multifunctional platforms. Finally, we outline the current challenges in optimizing microneedle-based immunotherapies and discuss future directions toward clinical translation.