Cheap, efficient, and stable hydrogen evolution reaction (HER) electrocatalysts have long been pursued, owing to their scientific and technological importance. Currently, platinum has been regarded as the benchmarked HER electrocatalyst. Unfortunately, the low abundance and high cost impede its industrial applications. Here, we synthesize bimetallic carbide Mo6Ni6C grown on nickel foam as a HER catalyst, delivering a low overpotential of −51 mV at −10 mA cm–2 in 0.5 M H2SO4 for more than 200 h, which is among the best reported benchmarked HER catalysts in acid to date. On the basis of experimental observations and theoretical modeling, we ascribe the good activity to the proper Gibbs free energy of adsorbed hydrogen (ΔG(H*)) for the carbon active sites and attribute the stability to the corrosion-stable Mo–Mo bonds in the crystal structure. This work demonstrates the possibility for Mo6Ni6C to be one of the best candidates for HER electrocatalysts in the large-scale electrolysis industry.