There is a pressing demand to explore alternative to Pt-based electrocatalysts for hydrogen evolution reaction (HER) in water electrolysis. In this study, an iron phosphide catalyst with periodically ordered mesoporous structure (meso-FeP) was fabricated via a nanocasting method for the HER. The as-prepared meso-FeP exhibited high electrocatalytic activity, affording 10 mA·cm current density at small overpotentials of 114 mV and 136 mV with the maintenance of its catalytic activity for at least 22 h in 0.5 M HSO and 1.0 M KOH, respectively. The outstanding performance is attributed to the high specific surface area (209.4 m g) derived from ordered mesopores, which endows the catalyst with abundant electrochemically active sites and accessible mass transport pathway. This work provides an efficient strategy to prepare mesoporous phosphides as high-performance hydrogen evolution catalysts.