Intraplanar heteroatom doping is an effective way to control the electronic structure and active sites of electrocatalysts by reducing the Gibbs free energy of the hydrogen evolution reaction (HER), as well as to improve the intrinsic electrical conductivity of the catalyst. Here, iron-doped tungsten disulfide (Fe-doped WS2) nanosheet arrays were synthesized on carbon cloth by solvothermal method. The experiment and first principle calculation results demonstrate that doping of iron can not only increase the charge transfer rate and reduce the interface transfer resistance, but also increase the active surface area and arouse the in-plane inert sites, thereby improving the HER activity of WS2. The optimal sample shows the overpotential of 166 mV (10 mA cm−2) and the Tafel slope of 82.2 mV dec−1 in 0.5 M H2SO4. This finding reveals that introducing dopant is a universal tool to regulate the electronic structure of WS2 and then to further improve its electrocatalytic activity.