Multistorey buildings with irregular plan are commonly constructed and are relatively more prone to damage caused by earthquake than regular buildings. It’s a known fact that the base isolated building outperforms the normal building. Hence, the objective of this study is to comprehend how base isolation affects a building with irregular plan response to near-fault ground motion. The study analysed a nine-story, C-shaped RC building with base isolation, which was simulated using the finite-element software SAP2000. In comparison to non-isolated buildings, the isolated building’s base shear was discovered to be lowered by 55.92 and 24.58% in X and Y directions, respectively. In isolated buildings, compared to non-isolated buildings, the inter-storey drift ratio was discovered to be reduced by 85.89% and 51.72% along the directions Y and X, respectively.