Rheumatoid arthritis (RA) is a chronic autoimmune disease that is characterized by uncontrolled joint inflammation and destruction of bone and cartilage. Previous studies have shown that C-X-C motif chemokine 10 (CXCL10) has important roles in RA development and that blocking CXCL10 expression effectively inhibits arthritis progression in animal models. However, clinical study using anti-CXCL10 monoclonal antibody (MDX-1100) to block CXCL10 expression in patients with RA did not show significant effectiveness. Therefore, we turned our attention to C-X-C motif chemokine receptor 3 (CXCR3), which is a receptor for CXCL9, CXCL10, and CXCL11, to treat RA. In the present study, administration of JN-2, our newly developed CXCR3 antagonist, ameliorated the progression of arthritis in a collagen-induced arthritis animal model. JN-2 also inhibited CXCR3-induced cell migration and pro-inflammatory cytokine expression of bone marrow–derived macrophages and CD4+ T cells in vitro. In addition, we found that CXCL10 formed an auto-amplification loop through activation of NFκB. Furthermore, Phosphorylation of p65 at serine 536 played an important role in the auto-amplification of CXCL10. Overall, the present results demonstrated that JN-2 decreased inflammation by inhibiting CXCR3-enhanced cell migration and pro-inflammatory cytokine expression, which then ameliorated arthritis progression.