An interbody fusion cage is crucial in spine fusion procedures, serving to restore physiological vertebral alignment and reestablish spinal stability. However, conventional fusion cages often face challenges related to insufficient osteointegration and the requirement for substantial bone grafting, which may result in incomplete fusion and prolonged recovery periods. In this study, we harnessed the osteointegration advantages of tantalum (Ta), in conjunction with advanced 3D printing technology, to develop a novel non-window-type Ta cage. The mechanical and biological characteristics of the cage were comprehensively evaluated through mechanical testing, in vitro cellular assays, and in vivo sheep anterior cervical discectomy and fusion models. The results indicated that the 3D-printed porous tantalum (3D-pTa) cage, with mechanical properties analogous to those of trabecular bone, exhibited superior bone ingrowth and osseointegration performance, achieving excellent intervertebral fusion without the need for bone grafting, thereby enhancing cervical vertebra stability. Moreover, we performed a pilot clinical trial to assess the performance of non-window-type 3D-pTa cages in single-level posterior lumbar interbody fusion. The results demonstrated that 3D-pTa achieved favorable clinical outcomes up to the 12-month follow-up period. These results highlight the significant clinical potential of the 3D-pTa cage for spinal fusion applications.