Indoxacarb is widely applied as an insecticide that poses a risk of environmental contamination, indicating a facile and selective probe needs to be developed for indoxacarb assay in environmental and food samples. In this work, fluorescent La:MnMoO4 perovskite oxide nanomaterials are synthesized and used as a rapid fluorescent probe to detect indoxacarb in vegetable and fruit samples. The as-prepared La:MnMoO4 perovskite oxide showed blue fluorescence at 413 nm upon the excitation at 330 nm, however the fluorescence of La:MnMoO4 perovskite oxide can be efficiently quenched by indoxacarb through the inner filter mechanism. The sensor showed a satisfactory linear relationship with increasing amounts of indoxacarb in the range of 2.5–60 µM (R2 = 0.99) with a limit of detection (LOD) of 62.99 nM, displaying good recoveries in the range of 97.35–99.61 %. The developed La:MnMoO4 perovskite oxide-based fluorescent sensor could electively be applied for on-site assaying of indoxacarb in agricultural and environmental samples.