Lateral flow immunoassay (LFIA) is a promising tool for rapid detection in the field of agricultural product analysis due to its advantages of cost-effectiveness and operational simplicity. In this work, Eu metal–organic frameworks (MOFs) were introduced to LFIA as a rapid detection method characterized by high stability and low interference. Key research objectives included strong fluorescence, ease of labeling, and the utilization of fluorescent probes. Eu-MOFs were synthesized in one step via the hydrothermal method, exhibiting a fluorescence lifetime of 163 μs and spherical particles with diameters ranging from 250 to 400 nm. These conditions fulfill the characteristics and requirements of LFIA. Eu-MOFs exploit the porous nature of MOFs to mitigate the drawbacks associated with complex crosslinking agents. This enables antibody proteins to be cross-linked merely upon contact, thereby simplifying the detection process. A time-resolved LFIA method was developed utilizing Eu-MOFs for the detection of aflatoxin B1 (AFB1) in corn, achieving a limit of detection (LOD, IC10) of 0.149 ng/mL. The accuracy and reliability of the Eu-MOFs-LFIA method were validated through comparisons with spiked concentrations during spiking and blind sample analyses, with verification conducted using ultra-high-performance liquid chromatography mass spectrometry (UPLC-MS). Furthermore, testing of real samples demonstrated that the Eu-MOFs-LFIA method can effectively facilitate rapid detection of AFB1 in corn.