Creating a synergistic catalyst via a combination of Pd or Pt with oxophilic metal compounds is a widely used strategy in the development of efficient electrocatalysts for the ethanol oxidation reaction (EOR). Herein, we report an experimental study of the effect of cobalt carbonate hydroxide (CCH) on the EOR performance of a Pd catalyst under alkaline conditions. A self-supported hierarchically structured nanocomposite consisting of a conductive carbon fiber cloth substrate, CCH nanowire arrays, and palladium nanoparticles is synthesized via a hydrothermal method followed by hydrolysis decomposition and reductive annealing treatments. Our study, for the first time, validates CCH as an effective promoter for the oxidative removal of the adsorbed carbonaceous intermediates and/or products on Pd. Direct anchoring of tiny Pd nanoparticles on the CCH nanowires with a large specific surface area guarantees the exposure of abundant accessible active sites and the strong interactions between the component phases, both of which are beneficial to optimize the synergistic effect. Benefiting from these unique features, the Pd/CCH catalyst exhibits significantly improved activity and durability toward the alkaline EOR compared to the commercial Pd/C catalyst.