DC-link voltage sensor is traditionally indispensable for each submodule of Cascaded H-bridge rectifier (CHBR) for capacitor voltage balancing control. This article proposed dc-voltage detection method, which only needs one voltage sensor, for all submodules’ voltages of CHBR based on multi-sampling scheme. In this method, only one voltage sensor is placed between two ends of the cascaded H-bridges. This sensor samples the total voltage variable at the specific time right after each switching action, which enables the best utilization of information from this sensor. Exponentially weighted recursive least square (ERLS) is used to decouple voltage information within one sampling interval. The updating rate of capacitor voltages based on this method is illustrated. The analysis shows that this method owns faster updating rate and higher detection precision compared to traditional voltage detection methods. Finally, a simulation of the single-phase CHBR is built to validate the correctness and effectiveness of the proposed strategy.