The optical wireless communication (OWC) technology has been widely studied to provide high-speed wireless connections in indoor environments. Compared with the downlink, the uplink faces more restrictions, such as the stringent power, complexity, and cost requirements. In this Letter, we propose a waveform index modulated OWC uplink with each waveform seen as a virtual transmitter. Extra data is transmitted via the index of selectively activated virtual transmitter, and the OWC uplink speed can be improved whilst achieving similar bit-error-rate (BER) performance. The waveform index modulated uplink is experimentally demonstrated in a near-infrared OWC system. Results show that up to 15 Gb/s data rate is achieved with the proposed waveform index modulated uplink, which increases the data rate significantly with similar power and BER.