The complexity of seismic structure response arises from the nonlinear soil behavior during earthquakes. Typically, seismic structural design disregards soil flexibility, assuming a fixed base. This study aims to explore and elucidate various methods for incorporating soil flexibility into the interaction between soil and structure, particularly focusing on its impact on the superstructure's response. The study entails analyzing a vertically geometrically irregular ten-storey building with four bays supported by a raft foundation, considering both fixed and flexible bases for soil–structure interaction, and comparing the outcomes with those of a conventional building. Three soil types, hard, soft, and medium hard, are utilized in this study of soil–structure interaction. Soil flexibility is integrated into analysis through the Winkler approach and the elastic continuum theory. SAP 2000 v24 is utilized for model development. The impact of SSI on structural parameters, namely base shear, natural time period, and lateral displacement, is examined also discussed. It is validated that the structure's response is altered not solely by its dynamic and seismic excitation features also by the external environment surrounding its base, encompassing interaction among the foundation, structure, and soil.