Multilevel converters (MCs) have been widely used in medium- and high- voltage applications in terms of their advantages, such as smaller voltage stress, higher voltage and current ratings of switching devices, and optimized harmonic characteristics. Among MCs, cascaded H-bridge multilevel converter (CHMC) is popular for its better flexibility and scalability. Therefore, this paper proposes a nearest level modulation (NLM)-based space vector pulse width modulation (SVPWM) algorithm for a three-phase CHMC. Compared with the traditional SVPWM algorithm, the proposed algorithm only needs to detect the dwelling modulation vector closest to the reference vector instead of detecting three active dwelling vectors at the same time. The proposed algorithm has strong real-time performance. Secondly, according to the equivalence between the SVPWM algorithm and the NLM algorithm, the duty cycles of the three active vectors are derived from three-phase duty cycles, and subsequently, the switch matrix expressions are obtained to directly determine the optimized switching sequences. Finally, the trigger pulses are generated. The proposed SVPWM algorithm is simplified, fast, and independent of level numbers. Finally, simulations and experiments verify the correctness and feasibility of the proposed algorithm.