Plasmonic nanoparticles are exciting and promising candidates for light-activated catalysis. We report herein the use of plasmonic nanocubes for the activation of molecular hydrogen and the hydrogenation of ketones and aldehydes via visible light irradiation at 405 nm, corresponding to the position of the plasmon band of the nanocubes, at 80 °C. Only 1 atm of molecular hydrogen is required to access, using catalytic amounts of silver, primary, and secondary alcohols, with complete chemoselectivty for CO over CC reduction. The resulting catalytic system was studied over a scope of 12 compounds. Exposure to other wavelengths, or absence of light failed to provide activity, thus proving a direct positive impact of the plasmonic excitation to the catalytic activity. By varying the irradiation intensity, we studied the relationship between plasmon band excitation and catalytic activity and propose a potential reaction mechanism involving plasmon-activated hot electrons. This study expands the scope of reactions catalyzed by free-standing plasmonic particles and sheds light on H2 activation by silver surfaces.