Flagellin is a potent immunogen that activates the innate immune system via TLR5 and Naip5/6, and generates strong T and B cell responses. The adaptor protein MyD88 is critical for signaling by TLR5, as well as IL-1 and IL-18 receptors, major downstream mediators of the Naip5/6 Nlrc4-inflammasome. Herein we define roles of known flagellin receptors and MyD88 in antibody responses generated towards flagellin. We used mice genetically deficient in flagellin recognition pathways to characterize innate immune components that regulate isotype specific antibody responses. Using purified flagellin from Salmonella, we dissected the contribution of innate flagellin recognition pathways to promote antibody responses towards flagellin and co-administered ovalbumin in C57BL/6 mice. We demonstrate IgG2c responses towards flagellin were TLR5- and inflammasome-dependent; IgG1 was the dominant isotype and partially TLR5- and inflammasome-dependent. Our data indicates a substantial flagellin-specific IgG1 response was induced through a TLR5-, inflammasome-, and MyD88-independent pathway. IgA anti-FliC responses were TLR5- & MyD88-dependent and caspase-1-independent. Unlike C57BL/6 mice, flagellin immunized A/J mice induced co-dominant IgG1 and IgG2a responses. Furthermore, MyD88-independent flagellin-induced antibody responses were even more pronounced in A/J MyD88−/− mice, and IgA anti-FliC responses were suppressed by MyD88. Flagellin also worked as an adjuvant toward co-administered ovalbumin, but it only promoted IgG1 anti-OVA responses. Our results demonstrate that a novel pathway for flagellin recognition contributes to antibody production. Characterization of this pathway will be useful for understanding immunity to flagellin and the rationale design of flagellin-based vaccines.