Chicken Interleukin-6 (chIL-6) is a multifunctional pro-inflammatory cytokine that plays a central role in regulating innate and adaptive immune responses in avian species. Although the avian IL-6 cytokine system differs structurally from its mammalian counterparts, chicken IL-6 functionally parallels members of the mammalian IL-6 family by signaling through receptor complexes involving gp130 to activate JAK/STAT pathways and drive acute-phase responses, B-cell differentiation, and inflammatory gene expression. In chickens (Gallus gallus), IL-6 is rapidly induced in response to bacterial, viral, and parasitic infections—including avian influenza virus, Newcastle disease virus, infectious bursal disease virus, Salmonella, and Eimeria species—and contributes to fever, hepatic acute-phase protein production, and leukocyte activation. Dysregulated IL-6 expression is associated with excessive inflammation, reduced growth performance, and increased morbidity, making it an important biomarker for disease severity, vaccine response, and flock health monitoring in poultry production. In animal health and research settings, characterization of chicken IL-6 supports studies of host-pathogen interactions, mucosal immunity, vaccine development, and immune modulation strategies aimed at improving disease resistance, productivity, and welfare in commercial poultry systems.