Convenient and accurate quantification of disease-relevant multitargets is essential for community disease screening. However, in the field of photoelectrochemical (PEC) sensors for multisubstance detection, research on the continuous detection of multiple targets using a polarity-switching mode is scarce. In this study, a multiplexed PEC bioassay was developed based on a target-triggered "anodic-cathodic-anodic" multiple-polarity-switchable mode. Employing miRNA-21 and miRNA-141 as model analytes, the photosensitive material combinations of Cu2O/gold nanoparticles (AuNPs)/TiO2 and CdS/AuNPs/TiO2 were successively formed through the specific binding of different whisker branches of Whisker-DNA to Cu2O-H1 and the CdS-tripod DNA ring, respectively. This process reverses the photocurrent polarity from anodic to cathodic and then back to anodic upon detecting different targets, resulting in the high-sensitivity quantification of various biological targets with reduced interference. To enhance the device's utility and affordability in community disease screening, integrating a capacitor and a multimeter-smartphone connection simplifies the assembly and reduces costs. In developing the PEC sensor, the device demonstrated linear detection ranges for miRNA-21 and miRNA-141 from 0.01 fM to 10 nM. Detection limits for miRNA-21 and miRNA-141 were established at 3.2 and 4.3 aM, respectively. The innovative target-triggered multiple-polarity-switchable mode offers adaptability for other multitarget detections by simply modifying the structure of the whisker branches and the combination of photosensitive materials.