Abstract Radio-over-fiber is a cost-effective support for the forthcoming 5G developments aimed to fulfill the ever-increasing demand for information. However, such systems are limited by transmission impairments that reduce the quality of communication. To enhance the system performance, an adaptive decision-feedback equalizer based on the least mean square algorithm is proposed in this work to compensate for frequency mismatch in the transmitter and receiver local oscillators in a radio-over-fiber transmission scenario when considering the latest 5G New radio standard. Simulation results in MATLAB exhibit a major impact from the equalization technique in improving the system performance in the presence of such a frequency offset, allowing the optical link to be extended from ∼100 km with no equalizer up to ∼690 km after equalization. Thus, it was demonstrated that the proposed adaptive equalization technique is a promising contender to enhance 5G-based Radio-over-Fiber data transmissions.