Osteoma is a benign tumor. Extracranial cases are very rare. Twelve cases have been reported by 10 different authors in the literature. To our knowledge, osteoma was never reported in the patella. In this article, we report a 61-year-old male patient who presented with a painless mass in the patella of his right knee, which appeared almost four years before and showed a progressive enlargement in the past six months. Range of motion (ROM) of the joint was limited. Marginal excision was performed under regional anesthesia and the histopathological evaluation of the lesion confirmed the diagnosis of osteoma. There were no postoperative complications and the ROM of the joint returned to normal. Patient was followed-up for 24 months without any recurrence. This case of peripheral osteoma identified in the patella is an example of an atypical presentation. Patella tumors may affect the extensor mechanism. Therefore, detailed examination should be performed and differential diagnosis should be established carefully.