A juvenile racing pigeon (Columba livia) was presented with drooping of the wing and inability to fly. On physical examination, the right shoulder joint was swollen. The pigeon was euthanatized and submitted for necropsy. An excessive amount of fibrin was present in the canalis triosseus with severe arthritis of the affected shoulder joint. A pure growth of Mycoplasma-like colonies was obtained on microbiological culture of the shoulder joint. A 16S ribosomal RNA gene-specific polymerase chain reaction assay was performed on the isolate and revealed 100% similarity with Mycoplasma columbinum. Although infectious arthritis in homing pigeons is primarily associated with paratyphoid and Streptococcus gallolyticus infection, clinical practitioners should consider the potential role of Mycoplasma columbinum in arthritis in pigeons.