In this paper, a tree growth optimization (TGO) algorithm is introduced to diminish the computational complexity of the partial transmit sequence in exploring the optimal phase factors. The proposed TGO algorithm is an efficient method for reducing the high peak-to-average power ratio of optical orthogonal frequency division multiplexing signals. The problem of the peak-to-average power ratio causes inter-modulation between sub-carriers due to the non-linearity of the fiber optics and some devices such as power amplifiers and analog-to-digital converter. The performance of the proposed algorithm is evaluated using a set of benchmarks and compared with several counterpart methods. The results reveal that the TGO outperforms its counterparts in terms of solution quality and computational complexity.