We report on the growth of ZnO nanowires on a p-type diamond substrate using nanoparticle-assisted pulsed laser deposition technique. Microstructural analysis on different growth stages reveals that the self-assembled 1D ZnO nanowires emerge on well-formed 2D hexagonal base with spiral-like structures. We explain the formation of screw-dislocation-driven spiral-like-hexagons invoking crystal growth velocities at different regions of the hexagons. High-resolution transmission electron microscopy and selective area electron diffraction studies show that the nanowires are single crystalline in nature and grow along 0 0 0 1 direction of the wurtzite hexagonal structure. Room temperature photoluminescence spectrum of the ZnO nanowire shows a strong near band edge emission at 3.2 eV with a linewidth of 136 meV. © 2014 IOP Publishing Ltd.