Developing efficient photocatalysts for the water splitting reaction is crucial in a fuel cell reaction. Herein, we present a facile road-map for one-pot fabrication of PtPd nanodendrite (ND) ornamented niobium oxynitride nanosheets (PtPd/NbON) for solar-driven water splitting. This was achieved by annealing Nb₂O₅ under NH₃ to form NbON nanosheets which were subsequently used as starting seeds for the simultaneous growth and self-assembly of PtPd NDs with the assistance of Pluronic F127. The water oxidation performance of PtPd/NbON was substantially superior to those of NbON and Nb₂O₅. This is ascribed to the combination of NbON with its great visible-light-harvesting properties and narrow band gap and the unique catalytic merits of PtPd NDs.