Autoimmunity affects ~10% of the global population. Current therapies suppress protective immunity and are non-curative. Antigen-specific therapies can selectively suppress autoreactive cells, preserving protective immunity. B cell dysregulation, a major driver of autoimmunity, remains largely untargeted. We hypothesized that targeting B cells with antigen-loaded microparticles enhances therapeutic efficacy. Here, we demonstrate that antigen-loaded acetalated dextran microparticles (AMP) surface-associate with B cells and enhance IL-10 secretion and MHCII expression, promoting tolerogenic antigen presentation. Leveraging this property, we developed a therapy using myelin oligodendrocyte (MOG35-55) peptide-loaded AMPs associated with B cells (MOG-AMP-B). Administering MOG-AMP-Bs in a late therapeutic model of multiple sclerosis resulted in unprecedented recovery, reducing central nervous system (CNS) inflammation, downregulating activated dendritic cells and macrophages and increasing regulatory T- and B cells. MOG-AMP-Bs did not reduce the ability of animals to respond to a viral infection, representing a highly effective antigen-specific therapy for restoring immune balance in autoimmunity. This study includes proteomics on the AMP particles after serum exposure, identifying complement proteins enriched on its protein corona.