Chloramphenicol (CAP) used in aquaculture poses a great threat to human health. In this study, a novel biosensing platform was proposed by Fe/Zn-MIL-88B with performance-enhanced for fluorescent/colorimetric dual-mode detection of CAP. Zinc was incorporated into the metal-organic framework to modulate its internal electronic structure, resulting in the formation of Fe/Zn-MIL-88B. This modification notably boosted its peroxidase-like activity, enhancing the colorimetric sensing capabilities. Simultaneously, Fe/Zn-MIL-88B exhibited excellent fluorescence quenching properties, when combined with upconversion nanomaterials and aptamers to enable a fluorescent sensing system. The composite materials were integrated into a three-dimensional folded microfluidic analyzer created a biosensing platform for ultrasensitive sensing of CAP. The results demonstrated that the dynamic response of the biosensing platform for CAP ranged from 0.5 to 1000 ng/mL, with the detection limits of 0.064 ng/mL (fluorescence) and 0.095 ng/mL (colorimetry), respectively. The work offers valuable insights into the further development of advanced biosensing platforms.