The increasing demand for sustainable and resilient construction practices in seismic areas calls for innovative retrofitting solutions utilizing renewable resources. This study presents an experimental investigation on the structural performance of masonry walls upgraded using a Natural Fiber Textile Reinforced Mortar (NFTRM) system based on jute fibers. Hollow brick masonry walls were strengthened through the application of jute fiber nets, jute-based diatons (transverse connectors), and a composite mortar incorporating 1% jute fibers by weight. In-plane cyclic shear tests were performed under constant vertical loads to evaluate the improvement in shear strength ultimate capacity. The results show that the NFTRM system significantly enhances the load-bearing performance compared to unreinforced walls, reaching an ultimate shear strength of approximately 2.7–2.9 MPa. The outcomes highlight the potential of bio-based reinforcement systems to provide an eco-friendly and effective alternative for masonry strengthening in seismic regions, promoting both sustainability and resilience.