We report the preparation and characterization of poly(p-aminobenzene sulfonic acid) (PABS) films doped with flavins (flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN), riboflavin (RF)). It is noted as PABS/flavins modified electrodes. In this study, the conducting polymer, PABS served as a matrix during the electropolymerization to synthesize PABS/flavin composite films. The synthetic, morphological and electrochemical properties of PABS/flavin films and PABS films were compared. Characterization was performed by cyclic voltammetry (CV), atomic force microscopy (AFM), scanning electron microscopy (SEM) and ultraviolet visible (UV–vis) spectroscopy. AFM and SEM images revealed that the incorporation of flavins significantly altered the morphology of the PABS films. UV–vis spectroscopy confirmed the presence of flavins within composite films. PABS/FAD composite modified glassy carbon electrode (PABS/FAD/GCE) is used to electrochemically detect NADH and NAD+. PABS/FAD/GCE showed excellent electrocatalytic activity for the oxidation of NADH and for the reduction of NAD+. At optimum conditions, the sensor has a fast response to NADH and a good linear response observed for NADH in the range from 10 to 300 μM. The cyclic voltammograms (CVs) waves of nicotinamide adenine dinucleotide reduction-oxidation (NAD+/NADH) reversible reaction was also observed.