Highly active and stable electrocatalysts to produce hydrogen through water splitting are crucial for clean energy systems but are still challenging. Herein, a novel self-templating strategy was proposed to synthesize one-dimensional nanoporous RhNi alloy nanowires through combining metallurgical eutectic solidification and microalloying with chemical dealloying. In-situ X-ray diffraction and ex-situ characterizations reveal that the Al matrix served as a template to guide the growth of the Al₃(Ni, Rh) nanowires during eutectic solidification of Al-Ni-Rh precursor and was completely removed in the dealloying process. Meanwhile, the nanowire morphology could be well retained and the dealloying of Al₃(Ni, Rh) led to the formation of nanoporous RhNi alloy nanowires. The length scale of the RhNi nanowires could be facilely regulated by changing the solidification conditions. More importantly, the RhNi catalysts show excellent electrocatalytic activity and stability towards hydrogen evolution reaction in both acidic and alkaline media, which has been rationalized by density functional theory calculations.