Versatile screen-printing expertise mixed with using a nano/materials coating for bettering electrode functionalities boosted the manufacturing of extremely delicate electrochemical sensors addressing the necessity for quick and easy-to-handle checks in numerous utility fields. Nevertheless, because of the large-scale manufacturing and disposable and single-use nature of those gadgets, their environmental footprint ought to be taken into cautious consideration. Herein, the progressive reuse of post-consumer polyethene terephthalate (PET) plastics instead substrate coupled with biochar as an environmentally pleasant and cost-effective modifier is described as a sustainable different for the manufacturing of sturdy electrochemical sensors. The great printability of reused plastics with graphite inks regardless of the chemical heterogeneity, totally different crystallinity, and floor roughness was demonstrated utilizing atomic drive microscopy and attenuated complete reflection Fourier remodel infrared spectroscopy. Functionalization with brewers’ spent grain biochar enabled the fabrication of extremely performing electrochemical sensors for nitrite detection in water having a restrict of detection and a restrict of quantification of three.3 nM and 10.3 nM, respectively, with a linear vary spanning from 0.01 to 500 μM, and good reproducibility (RSD% 8%). The progressive intervention of the biochar-multilayer system markedly enhanced the electron switch course of on the electrode interface whereas concurrently serving as an absorptive materials for the investigated analyte. This work lays a basis for repurposing end-of-life plastics for the electronics trade and presents a customizable reuse technique aimed to maintain the worth of plastics within the financial system and cut back waste and leakage into the pure setting.