One of the adipose tissue cytokines, adiponectin is a newly defined adipocytokin, which is involved in insulin, glucose and adipocyte metabolisms. It has been determined that the amount of adiponectin in the circulatory system decreases in obese and type 2 diabetic patients. In addition to this decrease, many diseases such as heart diseases, high blood pressure, diabetes, joint diseases, high cholesterol, respiratory disease, gallbladder diseases are associated with obesity. Early detection of a decrease in the level of Adiponectin with a biosensor may be a new target for the prevention and treatment of cardiovascular diseases, immune disorder, joint disorders, especially obesity-related pathologies. In the scope of this study, poly ethylene terephthalate (PET) sheets covered with indium tin oxide (ITO), a unique transparent conductive material, was used as a working electrode which, introduced an extremely cheap and flexible material for this purpose. 3-Glycidoxypropyltrimethoxysilane (3-GOPS), an effective organosilane agent, produced a stable layer to immobilize anti-Adiponectin onto the working electrode surface. The immobilization of anti-Adiponectin onto ITO sheets were proved by the techniques, Fourier-transform infrared spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The immunosensor prepared under optimal conditions gave a response in a wide range of concentrations (25 pg/mL-2500 pg/mL with a LOD value of 148 pg/mL) of Adiponectin. Finally, the designed biosensor was applied to real human serum samples and successful results were obtained.