Innovations in photoelectrode architecture can continuously increase surface area, enhance light absorption and improve charge transport, and thereby increase overall power conversion efficiency. In the past, nanostructures of varying complexities, from one-dimensional nanotubes, nanowires and nanorods, to two-dimensional films and nanonets, and three-dimensional (3-D) porous structures, were reported with superior performance. In this article, recent efforts and progresses on solar electrochemical water splitting by branched 3-D nanostructured materials were reviewed. Along with branched homogeneous nanostructures, recent successes were also summarised in advancing the field by branched heterogeneous nanostructures, including coupling narrow-bandgap semiconductors to wide-bandgap semiconductors and plasmonic metal/semiconductor-composited photoelectrodes, which make it possible to achieve combined functionalities not observed with single-component materials. To sum, these novel branched nanostructures represent a new generation of photoelectrodes for high-efficiency solar energy harvesting and conversion to clean chemical fuels and hold bright potential for a wide range of practical applications in renewable energy.