Hydrogen is a promising substitute for non-renewable fossil fuels. Producing hydrogen fuel by electrolyzing water is an effective strategy to address the growing environmental problems. Platinum (Pt) is still the most active electrocatalyst to catalyze the hydrogen evolution reaction (HER) in alkaline media. Herein, we demonstrate that ultrafine candied haws-shaped PtWNi nanoalloys modified with the Ni species (Nin+) could be formed in the alkaline electroactivation process of PtWNi alloys. Notably, the Ni species (Nin+) promoted the decomposition of water and produced hydrogen intermediates, which were then immediately adsorbed on the surface of Pt and recombined into molecular hydrogen. Moreover, these hydrogen intermediates also enhanced the instability of the HO-H bond, leading to an increase in the total activity.