In this paper, integrated transmitter modules with 9 V high-voltage light emitting diode (LED) chips and built-in hardware pre-equalization circuits are designed and fabricated for wavelength division multiplexing (WDM) visible light communication (VLC) system. The measured −3 dB electrical modulation bandwidths are 764.6 MHz, 929 MHz, 921.5 MHz and 756.6 MHz for the purple, blue, green and red channels, respectively, resulting in an aggregate bandwidth of about 3.37 GHz. Based on polar coding scheme combined with high-order quadrature amplitude modulation and orthogonal frequency division multiplexing (QAM-OFDM), experimentally, the maximum aggregate data rate for the offline VLC system exceeds 23.43 Gb/s in 1 m indoor free-space link and the bit error rates (BERs) of all wavelength channels are under 7% pre-forward error correction (pre-FEC) limit of 3.8×10−3. In particular, the blue-ray channel always presents zero BER, i.e. an infinity Q-factor, within the experiment condition range.