This research aims to evaluate the impact of pounding on seismic demands for neighboring irregular buildings with collinear alignment eccentricity and provide valuable recommendations for seismic design. To achieve this, a numerical simulation is conducted to calculate the effects of pounding on the seismic response requirements in different scenarios where two irregular adjacent buildings with eccentric center of mass are considered, plan irregularity is reflected with eccentricities between the rigidity center and mass center of the building’s superstructure. Adjacent buildings with three different heights involve four-, eight-, and twelve-story buildings with moment-resisting frame (MRF) structural system. To ensure reliable estimation of engineering seismic demands, three different ground motions, which are fully compatible with the design spectrum, are applied to different adjacent building configurations. A nonlinear time history analysis is performed to determine the response demands for different adjacent buildings with collinear alignment eccentricity, such as displacement, inter-story drift, story shear force, impact force, and acceleration responses. The Engineering Design Parameters (EDP) are thoroughly examined to gain a comprehensive understanding of the structural behavior and performance of the adjacent irregular buildings. The findings hold for all these scenarios, suggest that the colinear eccentricity of the irregular building in the closing/convergence direction, promotes the pounding and increases the number of impacts, while the eccentricity in the opening/divergence direction, reduces the pounding probability and the number of impacts between adjacent buildings. Moreover, the findings highlight the impact of eccentricity on peak acceleration responses and emphasize the importance of considering eccentricity in assessing the dynamic response of adjacent buildings with insufficient separation.