<p>Metronidazole (MZ) is a nitroimidazole antibiotic utilized to cure a numerous infection.&#xa0;But metronidazole presents significant health risks for both animals and human, due to its mutagenic, carcinogenic, and genotoxic properties.&#xa0;Furthermore, long-term use can lead to severe central nervous system issues.&#xa0;Thus, the concentration level of the drug must be monitored to avoid such health complications, highlighting the significance of developing rapid, accurate, and highly sensitive methods for detecting metronidazole levels. Herein, a polyglutamic acid (PGA) functionalized carbon black nanoparticle (CB NPs), CB NPs/PGA nanocomposite modified electrode-based electrochemical sensor for the quantification of MZ in animal feed is developed. The electrochemical performance of the proposed sensor was evaluated by differential pulse voltammetry (DPV), cyclic voltammetry (CV), and impedance spectroscopic analysis. The proposed sensor displayed a wide linear range of 500–10⁴&#xa0;nM with a 0.17&#xa0;µM limit of detection, and 0.35&#xa0;µM limit of quantification. This is the first to report on the synthesis of CB NPs/PGA nanocomposite and its application for the detection of MZ. The selectivity of the modified electrode to detect MZ while minimizing interference from various ions was assessed, exhibiting remarkable resilience, remaining unaffected even when the interfering ions were present at 100-fold concentrations.&#xa0;Additionally, after two successive weeks of storage, the proposed sensor showed no discernible reduction current (&lt; 1.4%), demonstrating an excellent stability. The developed sensor successfully detected MZ within 2&#xa0;min in differ animal feeds with recovery rates range of 96–99%. The proposed sensor lays a groundwork in critical domains like food safety regulation, veterinary medicine, and agricultural monitoring.</p> Graphical abstract <p></p>