Optical orthogonal frequency division multiplexing (O-OFDM) technology is widely used in visible light communication (VLC) to improve the data transmission rate. However, O-OFDM systems have high peak-to-average power ratios (PAPRs), which limit their system performance. First, this study uses unipolar optical orthogonal frequency division multiplexing (UO-OFDM) without Hermitian symmetry to solve the problems of low spectral efficiency and high computational complexity of the conventional asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) system. Second, the conventional partial transmission sequence (PTS) technique is applied to the UO-OFDM system to decrease its PAPR, and a genetic algorithm (GA) is used to optimize the PTS technique for solving high computational complexity and low efficiency in searching for the optimal phase rotation factor of the conventional PTS technique. The simulation results show that GA-PTS significantly reduces the time required to search for the optimal phase rotation factor compared to the conventional PTS technique, with a slight difference in the PAPR suppression performance. Compared to the time used by the ACO-OFDM system based on the GA-PTS algorithm, the time used by the UO-OFDM system based on the GA-PTS algorithm is reduced. With an increase in the maximum generation, the reduced time becomes more significant.