A facile one-pot hydrothermal route was presented for the synthesis of novel Ni3S2 hierarchical dendrites with a three-dimensional (3D) framework. Through adjusting the reaction temperature and reaction time, various morphologies of Ni3S2 nanostructures were obtained. The as-prepared Ni3S2 samples have been characterized with X-ray powder diffraction, Raman spectrum, scanning electron microscopy, and transmission electron microscopy. A possible growth mechanism was proposed to illustrate the formation procedure of Ni3S2 3D hierarchical dendrites. Moreover, the electrochemical performances of all the prepared samples used as supercapacitor electrodes were investigated by cyclic voltammerty and the galvanostatic charge/discharge tests. Interestingly, the Ni3S2 hierarchical dendrites electrode exhibits excellent electrochemical properties, which can be attributed to enough electroactive sites for redox action provided by special hierarchical dendrites with individual 3D framework.