The IL‐1 family member IL‐36α has proinflammatory and pathogenic properties in psoriasis. IL‐36α binds to the IL‐36 receptor leading to nuclear factor kappa B/mitogen activated protein kinase mediated cytokine release. The IL‐36R antagonist prevents recruitment of IL‐1 receptor accessory protein and therefore IL‐36‐dependent cell activation. In inflamed human tissue, we previously could show that resident B cells and plasma cells (PC) express IL‐36α. Further, fibroblast‐like synoviocytes (FLS) produced proinflammatory cytokines upon IL‐36α‐stimulation. We hypothesize an IL‐36‐specific crosstalk between B cells/PCs and FLS permitting a proinflammatory B cell niche. Here, we firstly demonstrated that B cell lines and B cells from healthy donors express IL‐36α and stimulation increased IL‐36α in B cells and primary plasmablasts/PCs. Moreover, FLS respond specifically to IL‐36α by proliferation and production of matrix metalloproteinases via p38/HSP27 signaling. Importantly, IL‐36R‐deficiency abrogated IL‐36α−induced production of inflammatory mediators in FLS and changed the intrinsic FLS‐phenotype. Using an in vitro co‐culture system, we could show that IL‐36R‐deficient FLS had a limited capacity to support PC survival compared to wild‐type FLS. Hence, we demonstrated an IL‐36R‐dependent crosstalk between B cells/PCs and FLS. Our data support the concept of initiation and maintenance of a proinflammatory niche by B cells in the joints.