Abstract The purpose of this paper is to evaluate the improved suction bucket foundation (ISBF) for the offshore wind turbine. The ISBF included the design of two types of internal compartments inside buckets with different aspect ratios (AP). A series of centrifuge tests were performed to investigate the lateral bearing behavior of ISBF in four types of sandy soils. Both static and cyclic lateral loads were applied by an electrical actuator in a load-controlled system. The first method interpolated the lateral bearing capacity from the load-displacement curve and reinforced the results with the stiffness-displacement relationship. Moreover, displacement rate was calculated and plotted to obtain the lateral critical and ultimate bearing capacity as the second method. During cyclic tests, the first several cycles changed the lateral displacement and stiffness significantly, whereas the last several cycles did not obviously affect them. It was demonstrated that the geometric designs of ISBF had limited influence on its lateral bearing behavior, but the soil conditions of the foundation did bring about an obvious difference. The lateral capacity of ISBF was further compared to original suction bucket foundation (OSBF), thereby illustrating the advantages of the ISBF in offshore wind turbine constructions.