The development of an effective, non-precious electrocatalyst for the hydrogen evolution reaction (HER) is highly desirable for the commercial application of hydrogen as a clean and renewable energy and remains a substantial challenge. Herein, a hierarchical nanowires array (HNA) of iron phosphide (FeP) nanowires coated with iron phosphide nanorods grown on a carbon fiber paper (CFP) was constructed which exhibited remarkable catalytic activity in the HER. The overpotential required for the current density of 20 mA cm⁻² is as small as 45 and 221 mV in acidic and basic solution, respectively, corresponding to Tafel slopes of 53 and 134 mV dec⁻¹. The effective catalytic activity of the CFP–FeP HNA in the HER, together with its long-term stability and nearly 100% faradaic efficiency in water electrolysis, make the CFP–FeP HNA one of the best non-noble electrocatalysts described to date. The prominent catalytic activity of CFP–FeP HNA is correlated to the large number of active sites for the HER, and the fast electron transport from the CFP to the FeP nanorods mediated by FeP nanowires.