Owing to the quality control mechanisms operating in the early secretory compartment, only native proteins are secreted. Despite the difficulties in assembling planar immunoglobulin M (IgM) polymers, antibody‐secreting cells can release up to thousands of IgM per second. The finding that secretory μ (μ_s) chains bind to ERGIC‐53, a lectin transporter that cycles in the early secretory compartment, suggested that ERGIC‐53 hexamers could provide a polymerization platform. Here, we show that ERGIC‐53 binds to the conserved Asn563 glycan in the C‐terminal μ_s tailpiece (μ_stp). Removal of this glycan inhibits ERGIC‐53 binding and results in the rapid formation of larger polymeric assemblies. In contrast, removal of the Asn402 oligosaccharides prevents both polymerization and secretion. ERp44, a chaperone that interacts with ERGIC‐53, binds to Cys575 in the μ_stp, providing a fail‐safe mechanism that retrieves unpolymerized IgM subunits and promotes polymerization. The coordinated action of ERGIC‐53 and ERp44 provides a way to improve the efficiency of IgM secretion without perturbing its fidelity.