<p>Developing a simple, rapid and sensitive rutin sensor is of great importance for the quality control or dietary guidance of some agriculture products. Herein, an electrochemical sensor for the quantification of rutin was developed based on the bimetallic nanoparticles with gold as core and platinum as shell. The nanoparticles were prepared by using MoS₂ nanosheets as heterogeneous substrate and reductant for the gold precursor. The morphology of the ultimate nanocomposite was tuned by the amount of gold precursor. With a relatively big amount of chloroauric acid, the nanocomposite exhibited a sea urchin-like core-shell morphology with monodispersity. Moreover, contributing to the large specific area and excellent conductivity of this nanocomposite, the modified electrode prepared with the bimetallic nanoparticles mediated with MoS₂ nanosheets exhibited a response almost twice that of the electrode modified with the single material. As results, the developed electrochemical sensor displayed a broad quantification range from 20 nM to 1 µM with a limit of detection of 3 nM and high sensitivity of 149.3 µA µM^− 1 cm^− 2. In addition, the sensor exhibited excellent stability and reproducibility. The recovery results for onion samples demonstrated the application promise of the sensor in various agriculture products.</p> Graphical abstract <p></p> <p>Adjusting the amount of HAuCl₄ results in two different materials. The performance of electrodes modified with MoS₂-Au₁₀₀@Pt or MoS₂-Au₃₀₀@Pt materials is compared. The electrochemical sensor developed by MoS₂-Au₃₀₀@Pt exhibits the highest sensitivity, and thus is applied to the determination of rutin in onion samples.</p>