The electrocatalytic selective hydrogenation of biomass-derived molecules is an important approach for synthesizing value-added chemicals. Herein, we synthesized carbon-supported platinum-modified molybdenum oxide nanoparticles (Pt-MoO3/C) to efficiently catalyze cinnamaldehyde (CAL) to cinnamyl alcohol. DFT results unveiled that the modified Pt regulated the surface electronic structure, favourable for the vertical adsorption of CAL.