Abstract: A series of K-CuZnZrO₂ catalysts were synthesized using co-precipitation and impregnation methods to investigate the influence of Cu content on the production of lower alcohols, specifically isobutanol, from syngas (CO + H₂). Among the products obtained using the K-CuZnZrO₂ catalysts, methanol and isobutanol were the primary products(comprising 95% of the total alcohols). The K-12%CuZnZrO₂ catalyst with the Cu mass fraction of 12% demonstrated the highest performance for isobutanol synthesis, with an isobutanol selectivity of 20.2% and a yield of 22.8 g/(L·h). Various characterization analyses indicated that altering the Cu component effectively regulates the Cu-Zr interaction. Electron transfer between Cu and amorphous ZrO₂ significantly promotes the reduction of Cu²⁺ while generating low-strength weak alkaline sites, which favor the formation of more highly dispersed CuO-ZrO₂ solid solutions. These solid solutions are critical for the synergistic catalytic synthesis of isobutanol via CO hydrogenation. An excess of Cu content disrupts the electronic and coordination structure of the CuO-ZrO₂ solid solution, weakens the Cu-Zr interaction, inhibits the growth of C—C chains, and ultimately reduces isobutanol selectivity. The results provide new perspectives for the design of efficient, highly selective, and stable catalysts for isobutanol synthesis.