Iron–nitrogen–carbon single-atom catalysts (Fe–N–C SACs) are widely acknowledged for their effective oxygen reduction activity, however, their activity requires further enhancement. Meanwhile, additional structural optimization is necessary to enhance mass transport and achieve higher power density in practical applications. Herein, using ZIF-8 as a template, we synthesized yolk–shell catalysts featuring complex sites of Fe single atoms and Cu nanoclusters (y-FeCu/NC) via partial etching and liquid-phase loading. The synthesized y-FeCu/NC catalyst exhibits high specific surface area and mesoporous volume. Combined with the advantages of highly active sites and yolk–shell structure, the y-FeCu/NC catalyst demonstrated outstanding catalytic performance in the oxygen reduction reaction, achieving a half-wave potential (E_1/2) of 0.97 V in 0.1 M KOH. As a practical energy device, Zn-air battery (ZAB) assembled with y-FeCu/NC catalyst achieved a remarkable power density of 356.3 mW·cm^–2, representing an improvement of approximately 28.5% compared to its solid FeCu/NC counterpart. Furthermore, it showcased impressive stability, surpassing all control samples.