According to structural engineers, the design and analysis of reinforced concrete structures have seen a tremendous transformation in the last several decades. Improving the buildings’ safety, performance, and resilience—especially in the face of unforeseen seismic events—has been the driving force behind these developments. This research looks at how well irregular reinforced concrete (RC) buildings with base isolation systems handle seismic loads. An overview of base isolators is provided at the outset of the research, focusing on how they help isolate buildings from the ground in an earthquake. Conventional approaches may not be able to handle the dynamic behaviour of irregular structures, which presents its own set of problems in seismic design. This project aims to determine how base isolation systems affect seismic performance in irregularly shaped buildings. Various base isolators and the development of structural engineering for reinforced concrete structures are discussed in the literature study. In the modelling phase, three models for base-isolated and fixed-base structures are created using ETABS. The response spectrum approach in ETABS, used for seismic analysis, sheds light on the structures’ dynamic behaviour. Periods for base-isolated structures significantly rise across all models, suggesting improved seismic performance, according to the comparison study. The circular frequencies prove that isolating the foundation is an excellent way to decrease stiffness and increase earthquake resistance. Implications for practice indicate that base-isolated buildings with lower circular frequencies have improved energy absorption and dissipation, which may result in less structural damage. Maximum X and Y story displacement is the next area of attention in the study, which shows that base-isolated buildings are better at limiting lateral movement during earthquakes. Reducing maximum storey drift values improves structural stability and reduces deformations, demonstrating that the base isolation technology successfully minimises seismic pressures. Base isolation is a viable seismic retrofitting solution for irregular structures because it consistently outperforms fixed-base structures regarding performance metrics like maximum storey drift values, reduced circular frequencies, and increased periods. The results highlight the possible advantages of implementing base isolation measures and have practical implications for building design and construction in seismically active areas.