Abstract: The development of a high-performance sensing platform for rapid and on-site detection of carbendazim (CBD) residues remains an urgent need in agricultural and environmental monitoring. In this work, a heterostructured NiMn-layered double hydroxide/molybdenum carbide (NiMn-LDH/Mo₂C) composite was synthesized through a facile one-step hydrothermal method, in which carbonate-intercalated NiMn-LDH nanosheets were in-situ grown on conductive Mo₂C. The composite was systematically characterized by SEM, TEM, XRD, and XPS. When modified on a screen-printed carbon electrode (SPCE), the NiMn-LDH/Mo₂C hybrid significantly enhanced the electron transfer rate and electrocatalytic activity toward CBD oxidation. The constructed sensor exhibited a wide linear response range from 0.001 to 230 μmol·L⁻¹ and an ultralow detection limit of 0.2 nmol·L⁻¹(3σ). It also demonstrated outstanding selectivity, repeatability, and long-term stability. Practical application in detecting spiked CBD in environmental water, fruits, vegetables, and soil samples yielded satisfactory recoveries of 95.00% ~ 105.20% with RSDs below 3.59%. This work not only provides a reliable and sensitive analytical tool for CBD monitoring but also offers a feasible strategy for designing high-performance electrochemical sensors based on LDH–carbide heterostructures.