Controlling the compositions and morphologies of the electrocatalysts were conventionally used for improving the catalytic activities. Here, visible-light-enhanced electrocatalytic water reduction reactions on semimetal bismuth (Bi) nanorods were achieved. The Bi catalyst not only exhibited an ideal Faradaic efficiency of 98% for electrocatalytic hydrogen production, but also acted as a light absorber for improving the activity even under light irradiation up to 740 nm. As a result, the solar-to-hydrogen conversion efficiency under simulated AM 1.5G illumination was reached to 0.82%, which is 2.7 times higher than that induced by plasmon Au nanoparticles. This conversion efficiency is attributed to the excellent solar light absorption property of Bi and the enhanced electron-transfer at the interface of Bi/electrolyte under irradiation. The low-cost Bi catalyst with the dual function could open a venue toward designing more-energy-efficient electrocatalysts for hydrogen production assisted by sunlight.