<p>Recent devastating earthquakes have exposed the limitations of conventional seismic design, which primarily ensures life safety but may fall short in preserving post-event functionality and reparability. Particularly in regions with vulnerable building stocks, the socioeconomic consequences of widespread structural damage, including prolonged downtime and reconstruction costs, underscore the urgent need for seismic-resilience-oriented assessment and design strategies. This paper presents a detailed seismic performance assessment of an eight-story reinforced concrete (RC) frame structure damaged during the 6 February 2023 Kahramanmaraş earthquakes. The building’s existing structural system and material properties were identified through comprehensive in situ investigations. These included foundation excavation, concrete core sampling, and reinforcement inspections carried out in accordance with relevant standards. Nonlinear performance analyses were then conducted to assess the building’s seismic adequacy. The results revealed deficiencies, prompting a retrofitting strategy that adds RC shear walls to improve lateral resistance and achieve resilience-based performance objectives. The study also documents typical damage patterns observed after the earthquakes. In addition to the pushover analysis, nonlinear time-history analyses were conducted to validate the structural response further and provide a comprehensive comparative evaluation. Furthermore, a comparative cost-benefit analysis was conducted to evaluate the financial feasibility of the proposed strengthening strategy against the total reconstruction of the structure. Most notably, it stands as one of the first comprehensive studies conducted after the February 6 Kahramanmaraş earthquakes to propose and implement a detailed retrofitting scheme for a damaged structure, providing valuable insights into strengthening strategies that can guide future engineering practice and policy.</p>