We report a one-step synthesis of a macroporous Cu-g/C3N4 nanofiber catalyst, in which Cu-nanodots (<10 nm) are well coupled with g/C3N4 nanosheets to form Cu-Nx nanorods on the macroporous carbon nanofiber scaffold. The catalyst with a high specific surface area of 514.9 m2 g-1 exposes abundant electroactive sites that facilitate the adsorption of oxygen intermediates and thus exhibits high ORR activity, such as a high half wave potential of 0.83 V and long-term stability over 1000 cycles. The catalyst is a potential substitute for noble metal catalysts.