<p>The pesticide residues in the soil and the environment pose severe threats to the quality of agriculture and environmental safety. This underscored the importance of selective and sensitive methods of detection. The experiment aimed at developing a valid and very sensitive electrochemical sensor to detect the herbicide and algaecide, Diuron, a phenyl urea. A calcium-doped zinc oxide in the form of nanostructures was utilized as a modifier, for making a modified carbon paste electrode. The electrochemical conduct of the analyte was considered applying the techniques of cyclic voltammetry and square wave voltammetry. Physicochemical characterization of the synthesized calcium-doped zinc oxide nanoparticles confirmed the composition and nanostructured morphology, signifying the enhancement in the electrochemical response of Diuron. In addition to that, the electrochemical and thermodynamic parameters were also determined through the study of a scan rate and temperature variation. The electrokinetic experiments showed that there was a diffusion-controlled reaction consisting of two electrons and two protons. The analytical functioning of the sensor was evidenced by a low detection limit of 3.4 nanomolar with a wide linear detection range. The water and soil samples analysis ensured reliability and effectiveness in Diuron quantification, highlighting its practical use in agricultural and environmental monitoring.</p> Graphical abstract <p></p>