Sino-nasal solitary extramedullary plasmacytoma (EMP) is a rare neoplasm with unpredictable progression to multiple myeloma. To improve the precision of irradiation delivery, preserving the healthy surrounding tissue and critical structures we used a CyberKnife® for the treatment of sinonasal solitary extramedullary plasmacytoma. We present the first case of sinonasal-EMP treated with CyberKnife®-stereotactic radiotherapy (SRT) with a complete remission without adverse events. Based on the post-therapeutic results and healthy tissue preservation, we believe that CyberKnife®-SRT represents a good therapeutic option for the treatment of sinonasal-EMP.