This paper presents the development and experimental validation of multi-junction cascaded vertical-cavity surface-emitting lasers (VCSELs) to achieve high power conversion efficiency. The authors demonstrate that a 20-junction VCSEL can achieve an efficiency of over 88% at room temperature, surpassing the highest efficiency reported for edge-emitting lasers (EELs). They fabricated 15-junction VCSELs and achieved a maximum efficiency of 74% at room temperature under nanosecond driving current, with a differential quantum efficiency exceeding 1100%, the highest reported for VCSELs. The study combines theoretical simulations and experimental results to show that the efficiency improvement in multi-junction VCSELs is due to the multiplicative increase in gain volume while resistance and internal losses do not increase proportionally. This research addresses the energy consumption issues of VCSELs and offers significant advancements in the field of semiconductor lasers.This paper presents the development and experimental validation of multi-junction cascaded vertical-cavity surface-emitting lasers (VCSELs) to achieve high power conversion efficiency. The authors demonstrate that a 20-junction VCSEL can achieve an efficiency of over 88% at room temperature, surpassing the highest efficiency reported for edge-emitting lasers (EELs). They fabricated 15-junction VCSELs and achieved a maximum efficiency of 74% at room temperature under nanosecond driving current, with a differential quantum efficiency exceeding 1100%, the highest reported for VCSELs. The study combines theoretical simulations and experimental results to show that the efficiency improvement in multi-junction VCSELs is due to the multiplicative increase in gain volume while resistance and internal losses do not increase proportionally. This research addresses the energy consumption issues of VCSELs and offers significant advancements in the field of semiconductor lasers.