A 60 GHz orthogonal frequency-division multiplexing (OFDM) radio-over-fiber (ROF) system based on companding transform technique is proposed and experimently demonstrated to reduce the peak-to-average power ratio (PAPR) of OFDM signals and improve the sensitivity of the receiver. The 2.5 Gb/s 60 GHz OFDM-ROF signals based on companding transform is transmitted over 50-km standard single-mode fiber in the system. The experimental results show that the PAPR of the OFDM signal is decreased by 3 dB at complementary cumulative distribution function (CCDF) level of 10-4, and the receiver sensitivity is improved by 2.3 dB for launch power of 12 dBm at the BER of 10-3 and without dispersion compensation.