The effect of microwave heating energy on the Ce0.78Gd0.2Sr0.02O2-δ (GDCSr) electrospun nanofiber composite cathode was studied. Two compositions containing 50 and 80 wt.% GDCSr nanofibers were mixed with LSCF6428 powder (L5G5 and L2G8). A temperature set of 900, 1000, and 1100 °C for 1 h were selected to perform microwave heating. The electrochemical performance was carried out at 500–800 °C. The phase composition and morphology of the composite cathode microstructure were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A porosity value close to 50% was achieved by the L5G5 composite cathode using the Archimedes method. As much 68.1 mA/cm2 of I0 and 1.6 Ω of resistance polarization were achieved by L5G5 cathode. The excellent collaboration between the unique properties of nanofibers and the selective heating properties of microwave energy enhances the electrochemical properties of composite cathode. Thus, a large number of triple boundary phase (TPB) sites can be effectively formed improving the transportation of oxygen ions into the electrolyte.