Electroactive materials with low costs, simplicity, eco-friendliness, and efficiency are highly desirable for a variety of applications, including energy conversion, energy storage, and non-enzymatic sensing. Through the use of garlic green leaf biomass, active molecules are extracted to enhance NiCo₂O₄ nanostructure electroactive properties via reducing, stabilizing, and capping agents. A NiCo₂O₄ nanostructure electroactive material was created using 5 mL, 10 mL, and 15 mL of garlic leaf extract heated hydrothermally. An evaluation of the material's morphology, crystallinity, and surface chemical composition, as well as the application of electrochemical tests aimed at detecting ascorbic acid (AA) without the use of enzymes in phosphate buffer solution with pH of 7.4. Pure NiCo₂O₄ has the morphology of nanorods which was transformed into thinner nanowires consisting of nanoparticles with the addition of garlic leaves extract. Biosensors without enzymes have the advantages of being easy to make, reproducible, and stable over those with enzymes. NiCo₂O₄ nanostructures fabricated with garlic leaf extract in a 10 mL volume are being developed as non-enzymatic AA sensors. The AA sensor presented here operates linearly from 0.5 to 8.5 mM with a detection limit of 0.01 mM. It was found that an AA sensor is highly selective, stable, repeatable, and capable of quantifying AA concentrations in various real-life samples.