Addressing the seismic vulnerability of structures is critical, especially for those built before the introduction of the current seismic regulations. In this context, the use of exoskeleton systems have emerged as a highly effective retrofitting solution. This approach not only improves a building's seismic resistance but also enables continued operation during the retrofitting process. Nevertheless, traditional seismic assessment methods based on pushover analyses might not accurately predict the seismic capacity of structures. As an alternative, Incremental Dynamic Analysis (IDA), a nonlinear dynamic method, is widely recognized for its accuracy and reliability in structural assessment. IDA evaluates structural response by relating an earthquake intensity measure (IM) to a corresponding damage measure (DM). This study employs IDA to assess the seismic performance of structural retrofitting systems, focusing specifically on exoskeleton systems. A self-centering, rocking steel-braced frame was used as a retrofitting solution to prevent major structural damage and minimize residual drifts. Seven ground motion records were analyzed to evaluate both the existing and retrofitted structures. IDA curves were developed for various damage limit states as defined by the HAZUS criteria. The results show that exoskeleton retrofitting systems substantially enhance structural stability and reduce the likelihood of failure. These findings validate IDA as a powerful tool for both design optimization and practical implementation, reinforcing its importance in the development of effective seismic retrofitting strategies.