Soil remediation containing numerous organic contaminants is of great significance to ecological environment. Herein, the synergetic effects of Ce–Mn/Al2O3 with different active components on catalytic thermal desorption of chlorobenzene in soil were investigated. The optimized Ce–Mn/Al2O3 drastically enhance the desorption efficiency of chlorobenzene, and the corresponding conversion reaches 100% within 1 h at a low temperature of 120 °C. The superior performance is ascribed to the formation of Ce–Mn solid solution during the calcination process, resulting in a certain lattice change to the generation of abundant oxygen vacancies and acidic sites. Combining with the analysis of in-situ diffuse reflectance infrared spectroscopy and gas chromatography-mass spectrometry, the final products of chlorobenzene are decomposed into CO2, H2O, Cl2 and HCl. This work sheds light on the rational design of highly-active catalysts for practical applications of sustainable soil remediation.