An accurate stochastic model of the optoelectronic and photonic section of the interferometric fiber-optic gyroscope is developed taking into account all noise and disturbances sources. The model is validated using experimental data taken from a prototype of the sensor integrating commercial-off-the-shelf components. The sensing element of the sensor prototype is a fiber coil with a length of 500 m. Experimental and numerically-calculated waveforms match very well demonstrating the model’s ability to accurately predict the experimental reality. The comparison has been carried out applying to the gyro prototype an angular rate of ±0.44 rad/s. Two different modulating signals, squared and sine-wave, have been used for the validation. The achieved results pave the way for the development of a complete model of the gyro, which also includes the readout electronics.