Non-precious　iron-nitrogen-carbon　(Fe-N-C)　catalysts　are　promising　for　replacing　expensive　and　scarce　platinum　(Pt)-based　catalysts　for　the　oxygen　reduction　reaction　(ORR)　in　polymer　electrolyte　fuel　cells.　However,　their　electrocatalytic　ORR　performance,　including　activity　and　stability,　still　cannot　meet　the　practical　demands.　To　make　improvements,　perceiving　the　synergistic　effects　can　play　an　essential　role　in　designing　advanced　Fe-N-C　catalysts.　In　this　paper,　a　comprehensive　insight　into　synergy　for　the　ORR　electrocatalysis　of　Fe-N-C　catalysts　is　reviewed,　which　permeates　into　three　aspects:　synergy　in　synthetic　strategies　to　increase　site　density,　enhance　intrinsic　activity,　and　improve　catalyst　stability;　synergy　in　active　sites　involving　Fe-based　sites,　non-metallic　sites,　and　peripheral　environments;　and　synergy　in　catalyst　layers,　including　the　catalyst　body,　ionomers,　and　additives.　This　review　can　provide　profound　viewpoints　on　the　synergy　for　the　efficient　oxygen　reduction　electrocatalysis　of　Fe-N-C　catalysts　and,　therefore,　effectively　guide　the　development　of　high-performance,　non-noble　carbon-based　catalysts　and　their　reliable　applications　in　electrochemical　energy　technologies.