Bimetallic catalysts based on nonprecious transition metals have attracted increasing attention because of their unique synergistic effects in catalytic reactions, but the understanding of the nature of synergistic effects and their roles in a specific hydrogenation reaction remains lacking. Herein, a series of bimetallic Cu_xCo_y/Al₂O₃ (x/y = 5:1, 2:1, 1:1, 1:2, 1:5) nanocomposite catalysts were fabricated via the successive calcination and reductive activation process of layered double hydroxide precursors. Their catalytic performance in the selective hydrogenation of bioderived ethyl levulinate to 1,4-pentanediol (1,4-PeD) depended sensitively on the chemical composition of bimetallic CuCo catalysts. The optimal bimetallic Cu₂Co₁/Al₂O₃ catalyst exhibited markedly improved catalytic activity and selectivity compared to monometallic Cu/Al₂O₃, as confirmed by its lower apparent activation energy barrier of 65.1 kJ mol^–1 of the rate-determining step and its high selectivity of 93% to 1,4-PeD. Detailed characterization analyses and intrinsic catalytic studies revealed that the presence of CoO_x species in the bimetallic Cu_xCo_y/Al₂O₃ catalysts enhanced the metallic Cu dispersion and H₂ activation ability. More importantly, the strong electronic interaction at the interface of Cu and adjacent CoO_x species modified the chemical states of Cu species to create proper surface Cu⁰/Cu⁺ distributions and, particularly, provided synergic catalysis sites of Cu and electron-deficient CoO_x species, which was primarily responsible for the excellent catalytic performance of bimetallic CuCo catalysts. The bimetallic CuCo catalysts exhibited good stability in both batch and fixed-bed continuous flow reactions. Furthermore, present CuCo nanocomposite catalyst could be applied to the highly selective hydrogenation of other carboxylic esters and lactones to synthesize valuable C4, C5, and C6 diols.