In this communication, we report a facile approach to constructing catalytic active hierarchical interfaces in one-dimensional (1D) nanostructure, exemplified by the synthesis of TiO2-supported PtFe-FeO(x) nanowires (NWs). The hierarchical interface, constituting atomic level interactions between PtFe and FeO(x) within each NW and the interactions between NWs and support (TiO2), enables CO oxidation with 100% conversion at room temperature. We identify the role of the two interfaces by probing the CO oxidation reaction with isotopic labeling experiments. Both the oxygen atoms (Os) in FeO(x) and TiO2 participate in the initial CO oxidation, facilitating the reaction through a redox pathway. Moreover, the intact 1D structure leads to the high stability of the catalyst. After 30 h in the reaction stream, the PtFe-FeO(x)/TiO2 catalyst exhibits no activity decay. Our results provide a general approach and new insights into the construction of hierarchical interfaces for advanced catalysis.