Abstract: In this study, we developed a sensitive electrochemical sensor for trace phosphoproteins monitoring in foods. The sensor (NH₂-TiO₂/CuFC-C/GCE (TIECS)) was composed of recognition element aminated titanium dioxide (NH₂-TiO₂) and three-dimensional (3D) nanocomposite (CuFC-C), which were prepared through electropolymerizing reducing carboxylated graphene oxide (rGO-COOH) and CuNPs, as well as nano-layer NH₂-TiO₂ on glassy carbon electrode (GCE) at room temperature. The optimal detection conditions were as follows: the electro-polymerization cycles of rGO-COOH were 5, the electrodeposition time of CuNPs was 400 s, the electro-polymerization cycles of NH₂-TiO₂ were 9, the buffer solution was at pH 6.5, β-casein underwent equilibrium adsorption for 30 minutes. Additionally, the detection voltage was maintained within the range of 0.2−1.0 V. Based on the above optimal conditions, a large linear detection range from 10⁻¹⁴~10⁰ mg/mL with a low detection limit (3.82×10⁻¹⁷ mg/mL) and with correlation coefficients (R²) of 0.9946 was obtained via the TIECS system. The sensor exhibited remarkable selectivity against common interfering proteins. Moreover, it demonstrated excellent reproducibility and long-term stability, with relative standard deviation (RSD) of 2.42% and 1.04% respectively. Compared with the traditional laser desorption ionization−time-of-flight mass-spectrometry (MALDI-TOF MS), this prepared sensor has advantages such as lower cost and greater ease of operation. It is well-suited for the rapid detection of trace phosphoproteins in food. The successful application of the TIECS sensing platform to actual samples provides a potential platform for evaluating the nutritional properties of various foods and developing the functional foods.