Inflammatory arthritis that developed following immune checkpoint inhibitor (ICI) therapy for cancer persisted for several months following cessation of ICI therapy and necessitated management by a rheumatologist. At 6 months follow-up, 20 out of 41 patients for whom data were available had active inflammatory arthritis. Overall, three-quarters of the 60 patients included in the follow-up study required immunosuppressive treatment for their inflammatory arthritis, which did not seem to affect cancer progression.