As a typical family of volatile toxic compounds, benzene derivatives are massive emission in industrial production and the automobile field, causing serious threat to human and environment. The reliable and convenient detection of low concentration benzene derivatives based on intelligent gas sensor is urgent and of great significance for environmental protection. Herein, through heteroatomic doping engineering, rare-earth gadolinium (Gd) doped mesoporous WO₃ with uniform mesopores (15.7–18.1 nm), tunable high specific surface area (52–55 m²·g⁻¹), and customized crystalline pore walls, was designed and utilized to fabricate highly sensitive gas sensors toward benzene derivatives, such as ethylbenzene. Thanks to the high-density oxygen vacancies (O_V) and significantly increased defects (W⁵⁺) produced by Gd atoms doping into the lattice of WO₃ octahedron, Gd-doped mesoporous WO₃ exhibited excellent ethylbenzene sensing performance, including high response (237 vs. 50 ppm), rapid response–recovery dynamic (13 s/25 s vs. 50 ppm), and extremely low theoretical detection limit of 24 ppb. The in-situ diffuse reflectance infrared Fourier transform and gas chromatograph-mass spectrometry results revealed the gas sensing process underwent a catalytic oxidation conversion of ethylbenzene into alcohol species, benzaldehyde, acetophenone, and carboxylate species along with the resistance change of the Gd-doped mesoporous WO₃ based sensor. Moreover, a portable smart gas sensing module was fabricated and demonstrated for real-time detecting ethylbenzene, which provided new ideas to design heteroatom doped mesoporous materials for intelligent sensors.