We constructed a self-powered and reagent-less electrochemical aptamer sensor for sensitive detection of aflatoxin B1 (AFB1). Here, the metal ion Mn2+ required for the DNAzyme to drive a DNA walker is wrapped in UIO-66(Zr)-(COOH)2 and AFB1 triggers the DNAzyme walking strands to automatically and continuously cut the tetraferrocene-labeled substrate strands, which results in a significant decrease in the electrochemical signal. Under the optimal conditions, the concentration dependence of AFB1 is linear in the concentration range of 0.1 pg mL-1 to 0.195 μg mL-1, and the limit of detection is as low as 4.8 fg mL-1. The sensor displayed good performance even for samples with a complex matrix, such as a peanut sample. The recoveries of AFB1 obtained ranged from 95.5 to 106.8%. The developed sensing platform is reagent-less, self-powered, and highly sensitive. It holds great potential for detection of AFB1 in environmental and food samples.