A partial lower inverted J sternotomy and an extended transseptal incision provide excellent exposure for minimally invasive mitral valve surgery. However, the extended trasnsseptal incision causes dividing the sinus node artery, which may result in conduction system disturbance and need for permanent pacemaker implantation. Therefore, there is a challenge in the patient who requires concomitant ablation for atrial fibrillation because of possible conduction system disturbance caused by extended transseptal incision. We describe a new strategy for combined ablation of atrial fibrillation with minimally invasive cardiac surgery by a transseptal approach to the mitral valve through a partial lower sternotomy incision. Cryoablation was performed using a T-shaped cryoprobe with a lesion set of pulmonary vein isolation and ablation of the left and right isthmus in performing mitral annuloplasty, tricuspid annuloplasty, and atrial septal defect closure through a limited sternotomy incision. This technique might minimize possible conduction system disturbance and provide good surgical result for the patients who undergo mitral valve surgery and ablation of atrial fibrillation.