Inadequate antibody responses and perturbed B cell compartments represent hallmarks of persistent microbial infections, but the mechanisms whereby persisting pathogens suppress humoral immunity remain poorly defined. Using adoptive transfer experiments in the context of a chronic lymphocytic choriomeningitis virus infection of mice, we have documented rapid depletion of virus-specific B cells that coincided with the early type I interferon (IFN-I) response to infection. We found that the loss of activated B cells was driven by IFN-I signaling to several cell types including dendritic cells, T cells, and myeloid cells. This process was independent of B cell–intrinsic IFN-I sensing and resulted from biased differentiation of naïve B cells into short-lived antibody-secreting cells. The ability to generate robust B cell responses was restored upon IFN-I receptor blockade or, partially, when experimentally depleting myeloid cells or the IFN-I–induced cytokines interleukin-10 and tumor necrosis factor–α. We have termed this IFN-I–driven depletion of B cells “B cell decimation.” Strategies to counter B cell decimation should thus help us better leverage humoral immunity in the combat against persistent microbial diseases.