A carrier-suppressed reflective coherent passive optical network (CS-R-CO-PON) for mitigating optical interference is presented. Using an external modulator, the optical carrier of the upstream signal was suppressed and unwanted optical interferences, including the carrier-induced optical beat interference and Rayleigh backscattering, were effectively mitigated. Through experimental verification, we demonstrated that the proposed CS-R-CO-PON with orthogonal frequency-division multiplexing (OFDM) has a tolerance to the optical interferences in the upstream transmission.