In this paper, a novel orthogonal frequency division multiplexing (OFDM) modulation scheme based on discrete Hartley transform (DHT) combined with optical spatial modulation (OSM) is proposed for visible light communication (VLC) systems. In the proposed scheme, the function of the conventional discrete Fourier transform (DFT) is fulfilled by the DHT and real constellation schemes such as binary phase shift keying (BPSK) and pulse amplitude modulation (PAM) can be used. Hence, real signals are generated and then modulated to two light emitting diodes (LEDs) by employing OSM. The zero-forcing (ZF) scheme and maximum a posteriori (MAP) scheme are employed in the receiver. Simulation results indicate that the proposed scheme can achieve the required performance in terms of bit error rate (BER). The performance of Non-DC-biased OFDM (NDC-OFDM), generalized LED index modulation optical OFDM (GLIM-OFDM), and the proposed scheme is compared. It is shown that the proposed scheme has lower complexity than NDC-OFDM, and shows better BER performance and higher design flexibility than GLIM-OFDM.