Introduction. Giant cell tumor of the bone is a rare benign lesion that infrequently affects the ribs, and if present, is usually located posteriorly. The rarity of this tumor poses diagnostic and therapeutic problems for physicians, especially when it is located in the anterior arc of the rib in close proximity to the breasts in female patients. Case Presentation. We report the case of a 32-year-old Asian female with a giant cell tumor of her anterior rib, presenting as a large inframammary mass. Computed tomography showed a tumor arising from the 7th rib anteriorly with marginal sclerosis, cortical destruction, and a soft tissue mass. She was treated with surgical resection, and the defect was reconstructed primarily. The surgical specimen measured 28.0 × 24.0 cm. The microscopic examination showed a large number of multinucleate giant cells scattered over the parenchyma. Patient recovered uneventfully and continues to be recurrence-free six years after surgical resection. Conclusion. We report the largest known case of giant cell tumor arising from the anterior aspect of a rib. We recommend including giant cell tumor in the differential diagnosis of chest wall masses especially in female patients, regardless of the size on clinical examination.