Highly dispersed Pd/N-doped carbon dots (Pd/NCDs) were successfully immobilized in the mesoporous channels of amino-functionalized dendritic mesoporous silica nanospheres (NMS). The synthesized Pd/NCDs@NMS catalyst exhibits outstanding performance in the catalytic reduction of 4-nitrophenol (4-NP), achieving a turnover frequency of 1461.8 mol·mol_Pd⁻¹·h⁻¹, with the conversion rate remaining above 80% after 11 cycles. Experiments and density functional theory calculations reveal that the NCDs significantly affect the electronic structure of Pd nanoparticles, leading to changes in the energy barriers for the adsorption of 4-NP at the Pd sites and the conversion of 4-NP reaction intermediates, which is a key factor contributing to the catalytic performance. This study offers a new strategy for synthesizing carbon-dot-modified metal-based catalysts.