Background: Mycetoma is a chronic infectious disease caused by bacteria or fungi which typically affects the skin, deep tissues, and bones. This case involves bone mycetoma in an immunocompetent patient, marking the first known instance of actinomycetoma caused by Gordonia rubripertincta. Case Report: A 25-year-old male presented with severe pain and deformity in his left foot, symptoms that began five years prior after stepping on a wire. Initial surgery provided temporary relief, but symptoms worsened over time. Doxycycline treatment was ineffective. Skin biopsies were performed. The patient was diagnosed with actinomycetoma, with Gordonia rubripertincta identified in culture. Although initial improvement was observed with amoxicillin–clavulanate treatment, the condition later worsened, requiring long-term penicillin therapy and eventual surgical excision. Despite treatment, symptoms persisted, leading to a bone biopsy that showed no microorganism growth. A six-week course of ampicillin–sulbactam and ciprofloxacin, along with offloading, decreased pain and stabilized radiological findings. Conclusion: Gordonia infections mean there is no universally established treatment protocol. This case underscores the diagnostic and therapeutic challenges associated with mycetoma, particularly in non-tropical regions.