An online derivatization followed by a disposable electrochemical sensor was used for the determination of arbutin (AR) in cosmetic products. The AR was chemically oxidized by MnO2 and subsequently reduced at inexpensive screen-printed carbon electrodes using a low detection potential which improved the selectivity of the method. The effects of various parameters, such as solution pH, detection potential, and flow rate of the mobile phase, were studied in detail. Under optimal conditions [pH 1.6 (0.1 M H3PO4), detection potential 0.0 V (versus Ag/AgCl), flow rate 0.6 mL/min], the linear range for AR was 0.1-1500 ppm (r2 = 0.999) with LOD of 30.06 ppb (S/N = 3). The practical application of the proposed method was demonstrated by the determination of arbutin concentration in commercial cosmetic products.