An effective electrochemical sensor was developed from triaminotriazine-based polyimide (PI) films as selective membrane for the detection of catechin (CT). Firstly, triaminotriazine-based PI films were synthesized from 2,4,6-triamino-1,3,5-triazine (TAT) and pyromellitic dianhydride by thermal imidization method with different monomer ratios. Structural and morphological of synthesized PI films were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. Prepared polyimide films were used as membrane for the preparation of the modified electrodes. Catechin (CT) selectivity behavior of polyimide-modified Pt electrodes was investigated by means of differential pulse voltammetry (DPV). DPV voltammograms showed that peak currents of the modified electrode increased proportionally with increase in CT concentration. TAT-PI-1/1 sensor showed high selectivity, a high regression coefficient (R value = 0.9982 ), good repeatability (RSD of 2.15%), and limit of detection 0.0152 mM for catechin determination in the presence of multiple interferent species (1 mM coumaric acid, ascorbic acid, gallic acid, lactose, sucrose, fructose, maltose and glucose). Moreover, the TAT-PI-1/1 sensor was employed to determine CT in real sample.