Spontaneous monodispersion of Fe species and their stabilization in reactive atmospheres remain a key challenge in catalytic syngas chemistry. In this study, we present a catalyst with spontaneously monodispersed Fe on ZnCr2O4, which shows remarkable performance in the syngas-to-aromatic reaction when coupled with a H-ZSM-5 zeolite. Monodispersed Fe increases the turnover frequency from 0.54 to 2.48 h−1 without sacrificing the record high selectivity total aromatic (80%–90%) at a single pass. This is enabled by the activation of CO and H2 at oxygen vacancy nearest to the isolated Fe site and the prevention of carbide formation. Atomic precise characterization and theoretical calculations shed light on the origin and implications of spontaneous Fe monodispersion.