Visible light communication (VLC) is emerging as a promising technology thanks to the superior advantages of light-emitting diodes. In this letter, an advanced asymmetrically clipped dc biased optical orthogonal frequency division multiplexing (AADO-OFDM) scheme with adaptive subcarrier assignment is proposed to accommodate the demands of multi-users. Additionally, the optimization of optical power allocation for AADO-OFDM under the constrained total optical power is investigated and formulated to maximize the tight lower bound of the total channel capacity. Simulation results show that compared with the schemes without optimal power allocation, the proposed scheme can maximize the lower bound of channel capacity.