Posterior shoulder fracture dislocation (PSFD) is a rare and challenging injury. Early diagnosis and treatment can prevent serious complications and disability, reducing the risk of avascular necrosis of the humeral head and joint destruction. Several treatment options have been proposed, depending on the patient’s age, duration of dislocation, humeral head bone defect, length of the metaphysis attached to the reverse Hill-Sachs, osteopenia and functional demand, and concomitant diseases. Open anatomic reduction and internal fixation is a suitable option, particularly in young and active individuals. Humeral joint replacement is recommended for non-fixable 3- or 4-part fractures, particularly in elderly individuals with low demand and osteoporosis. This article reports a case of closed, irreducible PSFD that was treated with open reduction and internal fixation using a plate and deltopectoral approach.