Posterior shoulder fracture-dislocation is a rare traumatic entity. Early diagnosis results in the adequate treatment of these lesions and prevents serious complications, such as avascular necrosis. Several therapeutic options have been proposed depending on the size of the humeral defect, duration of the dislocation, age of the patient, associated comorbidities, and functional requirements. For this kind of injury, early open anatomical reduction and stable internal fixation remain the optimum treatment option. Arthroplasty is often the last resort for active young patients, particularly in cases of avascular necrosis, humeral head complex fracture, or undiagnosed posterior shoulder dislocation. Here, we report a case of a complex posterior shoulder fracture-dislocation in a young man, which was treated surgically with open reduction and locked plate osteosynthesis using a deltopectoral approach.