We report a case of sternoclavicular joint infection with chest wall abscess in a 54-year-old female with right shoulder pain for one month. The patient had hypertension and newly diagnosed diabetes. Laboratory findings showed elevated inflammatory markers. Chest MRI confirmed infectious arthritis with abscess, and blood cultures isolated Methicillin-sensitive Staphylococcus aureus. After surgical drainage and 7-week antibiotic therapy, the patient improved. This case emphasizes considering sternoclavicular joint infection in persistent shoulder pain, especially with risk factors like diabetes.