Coupling low-temperature plasma technology with catalysts can significantly enhance air purification efficiency and mitigate the generation of secondary pollutants. In this study, mesoporous [Formula: see text]-Al2O3 supported Mn–Ce–Co ternary oxides were introduced into a widely employed tubular dielectric barrier discharges (DBD) reactor for indoor air purification. The plasma-catalytic degradation of HCHO exhibited the following degradation efficiency order: Mn–Ce–Co/[Formula: see text]-Al2O3 [Formula: see text] Mn/[Formula: see text]-Al2O3 [Formula: see text] Mn–Ce/[Formula: see text]-Al2O3 [Formula: see text] Co/[Formula: see text]-Al2O3 [Formula: see text] [Formula: see text]-Al2O3 [Formula: see text] Ce/[Formula: see text]-Al2O3 [Formula: see text] Plasma. When compared to plasma treatment alone, the catalyst resulted in a remarkable 1.8-fold enhancement under conditions of 3.0[Formula: see text]kV, [Formula: see text]C, 60% RH. Additionally, the concentrations of the by-products O3 and NO[Formula: see text] were significantly reduced by 88.2% and 93.3%, respectively. The synergistic interaction between Mn, Ce and Co oxides facilitated the formation and transportation of surface-reactive oxygen species, thereby contributing to the thorough oxidation of HCHO and organic intermediates during the plasma-catalytic process. Moreover, the high specific surface area offered by mesoporous materials enhanced the adsorption and catalytic activity towards HCHO.