Efficient electrocatalyst for oxygen reduction reaction (ORR) is an essential component for stable operation of various sustainable energy conversion and storage systems such as fuel cells and metal-air batteries. Herein, we report a facile preparation of meso/macroporous Co and N co-doped carbon nanofibers (Co-N-x@CNFs) as a high performance and cost-effective electrocatalyst toward ORR. Co-N-x@CNFs are simply obtained from electro-spinning of Co precursor and bicomponent polymers (PVP/PAN) followed by temperature controlled carbonization and further activation step. The prepared Co-N-x@CNF catalyst carbonized at 700 degrees C (Co-N-x@CNF700) shows outstanding ORR performance, i.e., a low onset potential (0.941 V) and half wave potential (0.814 V) with almost four-electron transfer pathways (n = 3.9). In addition, Co-N-x@CNF700 exhibits a superior methanol tolerance and higher stability (> 70 h) in Zn-air battery in comparison with Pt/C catalyst (similar to 30 h). The outstanding performance of Co-N-x@CNF700 catalysts is attributed to i) enlarged surface area with bimodal porosity achieved by leaching of inactive species, ii) increase of exposed ORR active Co-N-x moieties and graphitic edge sites, and iii) enhanced electrical conductivity and corrosion resistance due to the existence of numerous graphitic flakes in carbon matrix.