For real-time dosimetry in electron beam therapy, an integrated fiber-optic dosimeter (FOD) is developed using a water-equivalent dosimeter probe, four transmitting optical fibers, and a multichannel light-measuring device. The dosimeter probe is composed of two inner sensors, a scintillation sensor and a Cerenkov sensor, and each sensor has two different channels. Accordingly, we measured four separate light signals from each channel in the dosimeter probe, simultaneously, and then obtained the scintillation and Cerenkov signals using a subtraction method. To evaluate the performance of the integrated FOD, we measured the light signals according to the irradiation angle of the electron beam, the depth variation of the solid water phantom, and the electron beam energy. In conclusion, we demonstrated that the pure scintillation and Cerenkov signals obtained by an integrated FOD system based on a subtraction method can be effectively used for calibrating the conditions of high-energy electron beams in radiotherapy.