BACKGROUND: Immune checkpoint inhibitors (ICIs) have significantly improved cancer treatment outcomes but are associated with immune-related adverse events (irAEs), such as inflammatory arthritis (ir-IA). Management of ir-IA is evolving, with corticosteroids as the primary treatment, though some cases require steroid-sparing agents. AIMS: This study aimed to compare initial mean prednisolone doses and disease persistence over 12 months in patients with rheumatoid arthritis (RA)-like ir-IA managed by rheumatologists or oncologists. METHODS: This retrospective observational study involved patients who developed RA-like ir-IA after ICI treatment for advanced cancers between September 2015 and January 2019 at a tertiary hospital in Brisbane, Australia. Patient records were reviewed up to January 2020 to evaluate chronicity. Data were collected, and statistical analyses compared the management between rheumatologists and oncologists. RESULTS: A total of 871 patients received ICI and 246 had irAEs, with 20 developing RA-like ir-IA. Nine were managed by an oncologist and 11 by a rheumatologist. The mean dose of prednisolone commenced by a rheumatologist was 14 mg compared to 53.3 mg by an oncologist (P = 0.0058). Patients managed by a rheumatologist were more likely to receive conventional synthetic disease-modifying anti-rheumatic drugs (csDMARD) (odds ratio 16, P = 0.023). Thirteen patients required ongoing maintenance treatment, while seven had resolution within 12 months of disease onset. CONCLUSIONS: RA-like ir-IA comprised 8% of ICI-related irAEs. During the study period, patients managed by rheumatologists received lower initial prednisolone doses and more frequent csDMARD than oncologists. A multidisciplinary involvement between rheumatologists and oncologists in the event of ir-IA is crucial.