Perovskite oxide semiconductors have attracted tremendous interest in gas sensing due to their promisingproperties of tunable active sites, excellent catalytic ability and good structural stability. Nevertheless, the rapid synthesis of perovskite oxides and controlled regulation of their surface oxygenvacancies remains a great challenge. Herein, we report a novel metal–organic frameworks (MOFs) selftemplatestrategy for the rapid and large-scale preparation of LaFeO3 nanoparticles (MLaFeO3) withabundant oxygen vacancies. Benefit from the introduction of oxygen vacancies, the resultantMLaFeO3 gas sensor exhibit excellent formaldehyde (HCHO) sensing performance at a low operatingtemperature of 160 C, including high sensitivity (Rg/Ra = 8.9 @ 100 ppm), fast response/recovery rate(53 s/32 s), low detection limit (1 ppm) and excellent selectivity. Comprehensive density functional theory(DFT) calculation and spectral characterizations reveal that oxygen vacancies play a vital role in promotingthe adsorption and activation of O2 and HCHO molecules, and accelerate the chemical reaction onthe sensing materials surface. Most importantly, it proves the promising application of MLaFeO3 sensorin food safety assessment. This work not only provides a simple strategy for constructing oxygen vacanciesenriched LaFeO3, but also demonstrates the application potential of LaFeO3-based gas sensors in thefield of formaldehyde detection.