Herein, we demonstrate a highly efficient and stable bi-functional electrode based on flower-like hierarchical nanoporous nickel-cobalt oxide (NP-NiCo2O4) material for electrochemical water splitting reactions. The as synthesized spinel crystalline nanoporous-NiCo2O4 material enables improved electrocatalytic activity towards both water oxidation and reduction by taking the advantageous of hierarchical nanoporous structure, improved active sites, and electrochemical active surface area, high charge-transfer kinetics and structural durability. The bi-functional NiCo2O4 electrode exhibits augmented current densities and electrode durability with a high mass activity and low overpotential in overall water splitting in alkaline solution, comparable with most of the previously reported Earth-abundant transition metal oxide based catalysts. Based on our discovery in the present investigation we suggest that the flower-like hierarchical nanoporous NiCo2O4 Earth-abundant transition metal oxide electrode would certainly function as a new class of nanomaterials for competent electrochemical bi-functional water splitting catalysts.