An optical fiber-indium tin oxide (ITO) optoelectrode was proposed and first demonstrated in electrochemical luminescence (ECL) analyze. A transparent conductive ITO film was coated onto the surface of a bare optical fiber by magnetron sputtering. The optical fiber was realized as a working electrode and a detection device at the same time. Notably, the photoelectric analysis is integrated into the optical fiber electrode, providing more information about the analyte while greatly simplifying the device. The modulation of the ECL response intensity is monitored in real-time by applying different voltages to the fiber optic electrode with a response time of 2 s. In aqueous solutions, trace amount of O2 can be detected in real-time by the optical fiber ECL system. A wide detection range of 1 × 10−5 M to 1 × 10−2 M is obtained. Especially, the optical fiber-ITO electrode has great potentials in environmental analysis and bioassay.