The force-based design (FBD) methods depend on the prescribed guidelines of the codes, often based on assumptions and modification factors that may fall short of achieving targeted performance of structures, subjected to seismic forces. On the other hand, recently developed performance-based plastic design (PBPD) gives a direct approach. In PBPD method, initially pre-selected yield mechanism and performance level are considered and an energy balance principle is used to estimate the design base shear. In this paper, a humble effort has been made to assess the applicability of PBPD methodology in designing the vertical irregular reinforced concrete (RC) frame buildings. This study focuses to assess the seismic performances of setback RC building frames, using a 5 storey and 10 storey frames as examples, designed by the PBPD method, under nonlinear static pushover and nonlinear time history analysis. The findings are then compared with those obtained from frames designed by the FBD method. Parameters such as base shear, formation of hinges, storey displacement, interstorey drifts are evaluated to compare the efficacy of the PBPD method. The results indicate that the frames, designed by PBPD, show better performance compared to the FBD-designed frames and all responses are within limit. This study concludes that implementing PBPD methods in the design of setback RC buildings (low to medium rise) holds the potential to enhance the overall safety and reliability of buildings, particularly in high seismic zones.