Bisphenol A is a widely used endocrine disruptor known for its toxicity and prevalence in the environment. It contaminates drinking water, especially when plastic bottles are exposed to Sunlight. Rapid, on-site detection of BPA in drinking water is crucial for protecting human health and the environment. Herein, we developed an electrochemical sensor for detecting and monitoring bisphenol A in water bodies utilizing biobased materials. The device uses a biopolymeric membrane with agarose and gelified green tea tannins (GT/Agar). A sensitive part was made using this natural composite due to its high ability to attach bisphenol A to tannin monomers. Green tea tannins were purified and characterized through HPLC, FTIR, SEM, and AFM. The electrochemical activity of the GT-Agar/Au sensor is also evaluated by electrochemical impedance spectroscopy, cyclic voltammetry, square wave voltammetry and scan rate. Based on its redox signal under the optimal experimental conditions, this sensor has a detection range of 10 −16 M to 10 −4 M, a limit of detection of 1.52 to 10 −17 M and very high selectivity. The proposed sensor successfully determined BPA levels from ultra-trace concentrations in bottled water samples, achieving satisfactory recovery rates. Compared to the results obtained using HPLC, it demonstrates high reliability.