Cobalt (Co) nanoparticles anchored porous N-doped carbon nanosheets (Co@PNCS) were fabricated using a facile one-pot pyrolysis route and tested as high-performance cathode catalysts for Li-O2 batteries. The hierarchical structure was made of cobalt nanoparticles distributed in the crumpled porous carbon nanosheets. Uniformly distributed and exposed cobalt nanoparticles in the PNCS exhibited a higher electrocatalytic activity compared to Co nanoparticles anchored nitrogen-carbon materials (Co-N-C). Density function theory (DFT) calculations based on the interfacial model demonstrated that the active Co sites exhibited a more stable binding ability to discharge Li2O2 products than that of the active N sites, and Li2O2 could be reversibly formed and decomposed during cycling. Owing to optimal loadings of Co nanoparticles (16.03 wt%), the Co@PNCS-2 cathode exhibited a high specific capacity of 11,329 mAh g−1 and extended cycling life of 120 cycles, highlighting the great potential as cathode catalysts for Li-O2 batteries.