Feline Interleukin-1 Beta (IL-1β) is a potent pro-inflammatory cytokine produced primarily by activated macrophages, monocytes, and dendritic cells in cats (Felis catus) following recognition of pathogens or tissue damage. Synthesized as an inactive precursor (pro–IL-1β), it is cleaved into its active form by caspase-1 within the inflammasome complex and subsequently signals through the IL-1 receptor (IL-1R1), activating NF-κB and MAPK pathways that promote fever, leukocyte recruitment, acute-phase protein production, and amplification of inflammatory responses. In feline health, IL-1β plays a central role in inflammatory and infectious diseases including feline infectious peritonitis (FIP), chronic gingivostomatitis, inflammatory bowel disease, osteoarthritis, and bacterial or viral respiratory infections, where dysregulated IL-1β production can contribute to tissue damage and chronic inflammation. As a biomarker, IL-1β reflects innate immune activation and disease severity in clinical settings. In translational research, cats serve as valuable natural models for human inflammatory disorders, coronavirus-associated immunopathology (FIP), chronic oral inflammatory disease, and osteoarthritis, and characterization of feline IL-1β supports studies of inflammasome activation, cytokine-driven pathology, and development of targeted anti-inflammatory therapies relevant to both veterinary and human medicine.