Traditional active power sharing in microgrids, achieved by the distributed average consensus, requires each controller to continuously trigger and communicate with each other, which is a wasteful use of the limited computation and communication resources of the secondary controller. To enhance the efficiency of secondary control, we developed a novel distributed self-triggered active power-sharing control strategy by introducing the signum function and a flexible linear clock. Unlike continuous communication–based controllers, the proposed self-triggered distributed controller prompts distributed generators to perform control actions and share information with their neighbors only at specific time instants monitored by the linear clock. Therefore, this approach results in a significant reduction in both the computation and communication requirements. Moreover, this design naturally avoids Zeno behavior. Furthermore, a modified triggering condition was established to achieve further reductions in computation and communication. The simulation results confirmed that the proposed control scheme achieves distributed active power sharing with very few controller triggers, thereby substantially enhancing the efficacy of secondary control in MGs.