It is a crucial and current challenge to develop efficient metal sulfide bifunctional electrocatalysts for practical applications in direct borohydride-hydrogen peroxide fuel cells (DBHPFCs). In this study, a uniform nanoflower-like Ni3S2 is rationally designed and hydrothermally grown on the surface of a 3D nickel foam (NF) support without the need for additional nickel sources, and Pd nanoparticles are further reduced on the surface of nanoflower-like Ni3S2 with sulfur vacancies to form Pd/v-Ni3S2/NF electrode by NaBH4 reduction. The Pd/v-Ni3S2/NF electrode delivers a NaBH4 electrooxidation current density of 902 mA cm−2 at 0.85 V and a H2O2 electroreduction current density of 298 mA cm−2 at 0.65 V in alkaline solutions. Subsequently, Pd/v-Ni3S2/NF electrodes are assembled into DBHPFCs, yielding the optimal power density of 78 mW cm−2 and demonstrating superior long-term stability. These results fully indicate that the nanoflower-like Pd/v-Ni3S2/NF self-supported electrode with abundant sulfur vacancies is a promising bifunctional electrocatalyst for DBHPFCs. Display omitted •Pd/v-Ni3S2/NF was rationally designed by using a simple fabrication process.•Pd/v-Ni3S2/NF electrode delivers a NaBH4 oxidation current density of 902 mA cm−2.•Pd/v-Ni3S2/NF electrode delivers a H2O2 reduction current density of 298 mA cm−2.•Pd/v-Ni3S2/NF was assembled into a DBHFC with higher power density of 78 mW cm−2.•Sulfur vacancy exposed more active sites to achieve super performances.