<p>A novel and highly sensitive electrochemical sensor based on an electropolymerized bromocresol green (BCG) film-modified pencil graphite electrode (poly(BCG)@PGE) was developed for the determination of tinidazole (TNDZ). The electropolymerization of BCG on the electrode surface significantly enhanced the electrochemical response toward TNDZ by improving electron-transfer kinetics and increasing the effective surface area. The fabrication and surface characteristics of the modified electrode were systematically investigated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FT-IR). The electrochemical behavior of TNDZ was studied using CV and differential pulse voltammetry (DPV). Key experimental parameters affecting sensor performance, including the pH of the electrolyte solution, monomer concentration, and number of electropolymerization cycles, were optimized. Under the optimized conditions, the proposed sensor exhibited a wide linear dynamic range (LDR) from 0.4 to 500&#xa0;µM for TNDZ determination, with a high sensitivity of 1402 µA·mM⁻¹·cm⁻² and a low limit of detection (LOD) of 0.11&#xa0;µM. The practical applicability of the developed voltammetric sensor was successfully demonstrated by the determination of TNDZ in artificial blood, pharmaceutical formulation, and spring water samples. The obtained results showed satisfactory recoveries with high precision and accuracy, confirming the reliability and potential applicability of the poly(BCG)@PGE sensor for sensitive electrochemical monitoring of TNDZ in complex matrices.</p> Graphical abstract <p></p>