The incidence of double primary malignancies is very low, particularly, a case of synchronous carcinomas of the ipsilateral breast and lung. Determining whether to have a one-stage operation for ipsilateral breast cancer and lung cancer is a challenge for the surgeon. The current study presents a case of a 56-year-old female, with a rigid textured mass measuring approximately 18×20 mm above the areola of the right breast and chest CT showing a mass of 20 × 14 mm at the tip segment of right upper lobe of the lung. A diagnosis of a synchronous dual primary carcinoma of the right lung (cT1N0M0) and right breast (cT1N0M0) was made. The patient underwent a right breast-conserving surgery, sentinel node biopsy, and right upper lobectomy and lymphadenectomy with a video-assisted thoracoscopic technique simultaneously. To our knowledge, in the previous literature, there was no one-stage operation for ipsilateral, synchronous carcinomas of the breast and lung and only one reported case with left breast and right lung cancer underwent a one-stage operation. This report first presents the successful treatment of a case with synchronous primary breast and lung carcinomas on the same side of the body with a one-stage operation and therefore is educational.