Abstract: With the growing demand for complex porous metal components in fields such as aerospace, biomedical engineering, thermal management, and lightweight load-bearing applications, triply periodic minimal surface (TPMS) structures have emerged as a critical research focus in metallic additive manufacturing, owing to their advantages of low density, high specific strength, excellent energy absorption capacity, and high design flexibility. A systematic review was presented following the logical framework of “structural design–additive manufacturing processes-performance studies”. First, the basic characteristics and typical configurations of TPMS structures are outlined, and the design approaches of uniform, graded, and hybrid structures, together with their effects on structural performance, are analyzed. Second, the applications of material systems including Ti−6Al−4V, 316L stainless steel, AlSi10Mg aluminum alloy, and nickel-based alloys, as well as major additive manufacturing technologies including selective laser melting, selective laser sintering, and electron beam powder bed fusion, are summarized. Finally, the performance characteristics of metallic TPMS structures are reviewed in terms of mechanical properties, permeability and biological properties, and thermal management performance. Overall, metallic TPMS structures can achieve the integration of multiple functions, including load bearing, energy absorption, mass transfer, and heat transfer, through the synergistic optimization of geometric and process parameters. However, current studies still face challenges such as forming defects, dimensional deviations, powder entrapment, and limitations in performance prediction. Future research should further reveal the intrinsic relationships among structural parameters, manufacturing defects, and service performance to improve the accuracy of performance prediction, manufacturing consistency, and engineering reliability of metallic TPMS structures.