This study aimed to create a miniaturized electrochemical platform for detecting As(III) contamination in herbal medicines. To reduce the operational steps of modification and determination, only a single drop of mixed standard Au(III) and sample solution is proposed to perform the electrochemical measurements using a screen-printed graphene electrode (SPGE). Square wave anodic stripping voltammetry was employed to integrate the simultaneous modification and determination processes. To perform the measurement, As(III) and Au(III) migrate to the SPGE surface while the reduction potential is held at -0.5 V, forming an Au-As intermetallic alloy. Then, As is stripped off for the electrochemical determination of As(III). The total assay time is less than 3 min. Under suitable conditions, the electrochemical sensing system can detect As(III) at concentrations ranging from 0.1 to 3.0 ppm, with a limit of quantification and limit of detection of 0.1 and 0.03 ppm, respectively. The applicability and accuracy of the proposed sensor were verified by determining As(III) in herbal medicinal samples, and they were found to be in line with the standard method (ICP-OES). The benefits of simple operation, rapid detection, portability, and low cost (<1 USD) make this a more powerful tool for routine monitoring and on-site analysis applications.