Highly dispersed Pt-Co bimetallic catalysts were deposited on multi-walled carbon nanotubes (MWCNTs) by atomic layer deposition (ALD). High selectivity to cinnamic alcohol ( > 90%) was achieved with high conversion ( > 90%) in hydrogenation of cinnamaldehyde over an optimized Pt-Co/MWCNTs catalyst. The catalyst also showed both high activity and high selectivity in C═O activation ( > 90%) in selective hydrogenation reactions of other α, β-unsaturated aldehydes, which indicated that the bimetallic catalyst was a universal and highly efficient catalyst for these kinds of reactions. Further, through a series of experiments and density functional theory (DFT) calculations, the synergistic effects of Pt, Co, and MWCNTs were investigated. The results revealed that the interaction between Pt and Co NPs worked as an important role in the high selectivity in C═O activation, and the synergistic effect between Pt-Co and MWCNTs boosted greatly the activity of Pt-Co bimetallic catalysts.