Recently, increasing interest has been focused on one-dimensional (1D) magnetic nanomaterials that have significant anisotropic electromagnetic parameters and size effects that can be used to achieve improved shielding efficiency. In this study, the simple, low-cost and scalable synthesis of FeCo nanofibers is demonstrated by combining an electrospinning process with sequential thermal treatment involving calcination in air followed by reduction in H-2 atmosphere. A citric acid has an influence on the morphology of the electrospun product. The as-spun precursor nanofibers are transformed into CoFe2O4 and FeCo phases through the sequential thermal treatment while maintaining the fibrous shapes. To evaluate the electromagnetic (EM) wave-absorbing abilities of the FeCo nanofibers, epoxy matrix composites with the nanofibers are fabricated. The composites show excellent EM wave absorption properties where the power loss of the FeCo nanofibers increased to 20 GHz without any degradation.