Abstract: Perfluorooctanoic acid (PFOA) is an emerging persistent organic pollutant, which poses significant threats to ecosystem safety and human health due to its extensive application, strong bioaccumulation potential, and ecological toxicity. In this study, a novel molecularly imprinted electrochemical sensor (MIECS) for PFOA detection was successfully fabricated via in-situ electropolymerization of melamine (Mel) on a three-dimensional (3D) conductive substrate consisting of molybdenum disulfide and carboxylated multi-walled carbon nanotubes (MoS₂/MWCNTs). Owing to the excellent electrical conductivity and high specific surface area of MoS₂/MWCNTs, as well as the stable crosslinked network and recognition-enhancing effect of polymerized melamine (p-Mel), the proposed sensor exhibits a wide linear range of 0.005-1500 nmol/L and a limit of detection (LOD) down to 0.002 nmol/L for PFOA determination. Furthermore, it demonstrates superior selectivity, long-term stability, and good reproducibility. When applied to spiked recovery experiments of environmental water samples, the sensor achieves satisfactory recovery rates and high detection accuracy. This work provides a reliable approach for the sensitive detection of PFOA and holds great application potential in the field of environmental monitoring.