Efficiently converting CO2 into value-added chemicals remains a significant challenge due to its inert nature. Here, we present the rational design of Pd/NiCo2O4 hybrid nanocatalysts with diverse morphologies for highly efficient CO2 hydrogenation to formate. The synergistic combination of Pd and NiCo2O4 offers improved catalytic activity towards formate production. Remarkably, the observation of a morphology-dependent Pd-NiCo2O4 interaction, linked to the presence of oxygen vacancies in NiCo2O4, significantly contributes to our understanding of catalytic activity. The rose-like Pd/NiCo2O4 catalyst achieves an impressive formate yield (85.3 molformate moltotalPd−1 h−1) due to its low oxygen vacancy concentration and subsequent generation of less positively-charged Pd species, emphasizing the crucial role of oxygen vacancies in hybrid nanocatalyst performance. These findings were further validated through density functional theory calculations, providing valuable insights into the design and optimization of nanocatalysts for CO2 hydrogenation. This contributes to the development of efficient and sustainable processes for CO2 utilization in the production of formate and other valuable chemicals.