Tailoring molybdenum selenide electrocatalysts with tunable phase and morphology is of great importance for advancement of hydrogen evolution reaction (HER). In this work, phase- and morphology-modulated N-doped MoSe /TiC-C shell/core arrays through a facile hydrothermal and postannealing treatment strategy are reported. Highly conductive TiC-C nanorod arrays serve as the backbone for MoSe nanosheets to form high-quality MoSe /TiC-C shell/core arrays. Impressively, continuous phase modulation of MoSe is realized on the MoSe /TiC-C arrays. Except for the pure 1T-MoSe and 2H-MoSe , mixed (1T-2H)-MoSe nanosheets are achieved in the N-MoSe by N doping and demonstrated by spherical aberration electron microscope. Plausible mechanism of phase transformation and different doping sites of N atom are proposed via theoretical calculation. The much smaller energy barrier, longer HSe bond length, and diminished bandgap endow N-MoSe /TiC-C arrays with substantially superior HER performance compared to 1T and 2H phase counterparts. Impressively, the designed N-MoSe /TiC-C arrays exhibit a low overpotential of 137 mV at a large current density of 100 mA cm , and a small Tafel slope of 32 mV dec . Our results pave the way to unravel the enhancement mechanism of HER on 2D transition metal dichalcogenides by N doping.