We demonstrate impressive performance of photoanodes comprising ZnO nanowires grown over nickel fibers for efficient water splitting. The photoanode is substrate-free and flexible, exhibiting excellent stability (similar to 98%) in photocurrent density even after 1000 bending cycles. The hierarchically structured ZnO nanowires on nickel microfibers synergistically provide many accessible electrochemical sites and enhance the photocurrent density to 1.14mA/cm(2) at a voltage of 0.4V vs. Ag/AgCl. The one- and two-dimensional structures of the ZnO nanowires over nickel microfibers enable an efficient charge-transport mechanism that supports high light-harvesting efficiency. Scanning and transmission electron microscopy are used to study the morphologies of the samples in detail, while X-ray diffraction confirms the metallic state of Ni and the crystallinity of ZnO.