Binary transition metal dichalcogenides (TMDs) have emerged as efficient catalysts for the hydrogen evolution reaction (HER). Co-based TMDs, such as CoS₂ and CoSe₂, demonstrate promising HER performance due to their intrinsic metallic nature. Recently, the ternary electrocatalysts were widely acknowledged for their prominent efficiency as compared to their binary counterparts due to increased active sites caused by the incorporation of different atoms. Herein, we successfully grew the ternary CoS_2xSe_2(1−x) (x = 0.67) nanowires (NWs) on a flexible carbon fiber. As a superior electrocatalyst, ternary CoS_2xSe_2(1−x) NWs arrays demonstrated excellent catalytic activity for electrochemical hydrogen evolution in acidic media, achieving current densities of 10 mA cm⁻² and 100 mA cm⁻² at overpotentials of 129.5 mV and 174 mV, respectively. Notably, the high stability of CoS_2xSe_2(1−x) NWs suggested that the ternary CoS_2xSe_2(1−x) NWs are a scalable catalyst for electrochemical hydrogen evolution.