Vertical geometric irregular reinforced concrete (RC) buildings are widely used in structural engineering due to their aesthetic appearance and functional characteristics. Indeed, improving their reliability and seismic performance is of crucial interest and has even become a necessity. This research study underlines the importance of using shear walls (SW) as a fundamental means of reinforcement for this type of structure. Twenty models, including ten with SW and ten without SW, of mid-rise buildings with setback irregularity were considered for this purpose, and fragility analyses were carried out, using a non-linear procedure, to highlight the potential usefulness of shear walls for irregular structures. The results of this work clearly indicate that the dynamic behavior and response of buildings have been improved by the use of shear walls. The fragility study reveals that for some cases the damage probability is reduced, with the difference exceeding 13% for the majority of models, and for some cases the differences are highly significant, ranging from 30% to 60%. This shows the benefits of incorporating shear walls into the design phase of irregular buildings.