<p>Monitoring lambda-cyhalothrin (LC) is essential for environmental and public health. Herein, LC was selected as the template to fabricate a molecularly imprinted layer on magnetic nanozymes Fe₃O₄-Cu, resulting in a magnetic molecularly imprinted nanozyme (SMIPs@Fe₃O₄-Cu). In the presence of hydrogen peroxide, non-fluorescent terephthalic acid could be catalyzed by SMIPs@Fe₃O₄-Cu and converted into its fluorescent derivative, 2-hydroxyterephthalic acid (2-HTA). LC could occupy the imprinted cavities, thereby reducing the peroxidase-like activity of SMIPs@Fe₃O₄-Cu and decreasing 2-HTA production. Additionally, LC could quench the fluorescence of 2-HTA via electron transfer. The dual quenching mechanism significantly improved the sensitivity of the constructed selective sensing platform based on SMIPs@Fe₃O₄-Cu, with an extremely low limit of detection (5.03 ng/L) for LC. Furthermore, the applicability of the proposed method was evaluated using fruit and vegetable samples, achieving satisfactory recoveries (97.8%–103%) and low relative standard deviations (0.498%–4.48%). This efficient sensing platform exhibited superior performance compared to previous literature, making it beneficial for detecting LC in complex samples.</p>