At present, Li-O2 batteries deliver the highest energy density among rechargeable batteries, but main obstacles including low discharge capacity, high charge overpotential and low cycle stability still exist. It is essential to exploit a desirable electrocatalyst with specific structure and activity to partially solve the problems of Li-O2 batteries. In this work, an efficient catalyst of porous nanocubes La0.9Co0.8Ni0.2O3−x perovskite (PN-LCN) has been synthesized by a facile hydrothermal method, with the special porous morphology and abundant oxygen vacancies. Hence, Li-O2 batteries with the PN-LCN can deliver a specific discharge capacity of 14,360 mAh g−1 with a coulombic efficiency of 88% and a cycle stability of over 100 cycles at 300 mA g−1, which is much better than that with dense particles La0.9Co0.8Ni0.2O3-x perovskite (DP-LCN) at the same current density. The PN-LCN with special morphology and abundant oxygen vacancies is demonstrated to be an efficient catalyst toward both oxygen reduction reaction and oxygen evolution reaction, with promising the application in Li-O2 batteries.