Porous conductive ion-selective membranes (PCIMs), as key components of sustainable energy devices, have attracted widespread research interest owing to their unique pore structures and properties for achieving low-resistance high-ion-selectivity transport. However, the fabrication of high-efficiency PCIMs remains challenging, and the intricate relationship between the structural properties of PCIMs and its pivotal influence on the performance of energy devices is not well explored. This review focuses on emerging PCIMs with sub-nano/nanometer pores, particularly their design strategies, and fabrication processes. First, the theorical mechanisms underlying ion transfer in confined pores is comprehensively discussed. Subsequently, the effect of a series of pore characteristics—including size, charge, geometry, orientation, and durability on ion-selective transport and their regulation strategies are discussed and summarized. Then, effective and universally known methods for designing and adjusting PCIMs containing intrinsic pores, induced pores, and composite pores are highlighted. Furthermore, the progresses of PCIM applications in emerging electrochemical energy devices including fuel cells, flow batteries, Li-ion batteries, and concentration batteries are summarized. Overall, this review aims to provide a valuable reference for scholars and researchers dedicated to the study of PCIMs, thereby contributing to the ongoing progress in this field.