The Phase-II benchmark cable-stayed bridge problem evaluates the effectiveness of the friction pendulum system (FPS) and the polynomial friction pendulum isolator (PFPI) in reducing seismic effects. By varying the isolator parameters, this study evaluates their performance under various loads and incident angles. When these isolators are deployed, there is a considerable reduction in base shear, overturning moments, and seismic responses. MATLAB and Newmark's step-by-step integration approach are used for seismic response analysis. A comparison of the seismic responses of the isolated benchmark bridge reveals that PFPI outperforms FPS. The effect of the isolation time period on structure reaction is determined by the individual isolator type and the earthquake ground motion parameters. This research provides useful insights into the behavior of FPS and PFPI systems, emphasizing the PFPI’s potential as an effective seismic control option for cable-stayed bridges.