P-doped ZnO one-dimensional (1D) nanorods (NRs), grown by simple hydrothermal method, show highly enhanced ultraviolet photoluminescence (UV PL) property as compared to the undoped ZnO sample. A detailed in-depth understanding on the mechanism behind the enhancement has been conducted by performing experimental analyses on power dependence of and annealing effect on the emissions, low temperature PL (LTPL), and electrical I–V characteristics of various P-doped ZnO NR samples. The doped NR samples retain hexagonal wurtzite structure and similar morphology as that of the undoped one. The UV/vis PL intensity ratio becomes 9 for as-grown sample and 22 for annealed 2% P-doped sample, which is one order higher than that of the undoped ZnO sample. Correlation of the LTPL and electrical I–V characteristics reveals that the high enhancement in the UVPL is due to recombination via shallow acceptor complex defects of P_Zn–2V_Zn type.