<p>In this study, an electrochemical sensor was developed for the simultaneous analysis of levofloxacin and paracetamol. The bare carbon nanotube electrode (BCNTE) was modified with L-arginine (L-AGMCNTE) using an electropolymerized technique. This modification showed improved sensitivity and a notable increase in the oxidation response of levofloxacin with the current response of 17.78 µA in 0.2&#xa0;M phosphate buffer solution at pH 7.0. The electrochemical characteristics of both BCNTE and L-AGMCNTE were assessed using techniques, such as cyclic voltammetry, differential pulse voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy. The study of scan rate showed that the oxidation process is controlled by adsorption. Numerous experimental aspects, including the study of pH and variation of levofloxacin concentration, were adjusted to enhance the performance of the sensor. L-AGMCNTE showed excellent electrochemical properties, such as attaining a good limit of detection of 0.34 × 10⁻⁶&#xa0;M and a limit of quantification of 1.14 × 10⁻⁶&#xa0;M, while showing strong resistance to interference, such as metal ions and organic compounds and metal ions. Additionally, L-AGMCNTE showed good reproducibility, repeatability, and stability. When applied to real sample analysis, the fabricated sensor provided reliable and accurate results. Notably, this study introduces a novel L-AG electropolymerized carbon nanotube platform for the simultaneous detection of levofloxacin and paracetamol, offering a simple yet highly sensitive and selective approach for pharmaceutical analysis.</p> Graphical abstract <p></p>