The quantization of Hall conductivity, epitomized by the integer quantum Hall (IQH) and quantum anomalous Hall (QAH) effects, has long been associated with insulating topological states. Recent experiments have demonstrated half-quantized anomalous Hall responses coexisting with metallic conduction. Here, we experimentally demonstrate an interface-governed QAH metal, in which a near-quantized anomalous Hall conductivity (AHC) coexists with substantial longitudinal conduction. By sandwiching a magnetic insulator between two non-magnetic topological insulator layers, we realize a metallic heterostructure exhibiting an AHC plateau near $e^2$/h, despite the absence of a global insulating gap. We further demonstrate a hierarchy of quantum anomalous Hall-metal plateaus through “Lego-like” heterostructure engineering and magnetization tuning, with a sign-tunable Hall response determined by gapped topological-insulator/magnetic-insulator interfaces and persisting despite metallic dissipation. These results establish interface counting, rather than a global insulating Chern band, as an organizing principle for quantized Hall responses in metallic topological heterostructures.