Abstract: The remarkably high theoretical energy densities of Li-O₂ batteries have triggered tremendous efforts for next-generation conversion devices. Discovering efficient oxygen reduction reaction and oxygen evolution reaction (ORR/OER) bifunctional catalysts and revealing their internal structure-property relationships are crucial in developing high-performance Li-O₂ batteries. Herein, we have prepared a nanoflower-like Ni₅P₄@NiSe₂ heterostructure and employed it as a cathode catalyst for Li-O₂ batteries. As expected, the three-dimensional biphasic Ni₅P₄@NiSe₂ nanoflowers facilitated the exposure of adequate active moieties and provide sufficient space to store more discharge products. Moreover, the strong electron redistribution between Ni₅P₄ and NiSe₂ heterojunctions could result in the built-in electric fields, thus greatly facilitating the ORR/OER kinetics. Based on the above merits, the Ni₅P₄@NiSe₂ heterostructure catalyst improved the catalytic performance of Li-O₂ batteries and holds great promise in realizing their practical applications as well as inspiration for the design of other catalytic materials.