Commercially available carbon blacks serve as effective metal-free catalysts for the selective hydrogenation of carbon–carbon multiple bonds under aerobic conditions using hydrazine as the terminal reductant. The reaction, which proceeds through a putative diimide intermediate, displays high tolerance to a variety of functional groups, including those sensitive to nucleophilic displacement by hydrazine, aerobic oxidation, or hydrazine-mediated reduction. Hydrazine chemisorbs strongly to the carbon surface, attenuating its native oxidative reactivity and allowing for selective hydrogenation. The catalytic sequence established here effectively umpolungs the reactivity of carbon, thereby enabling the use of this low-cost material in selective reduction catalysis.