In this work, we have developed amino-functionalized copper-based metal–organic frameworks (NH₂-Cu-MOFs) for the detection of hypochlorite (ClO⁻). NH₂-Cu-MOFs were synthesized using a one-pot hydrothermal method, and they exhibit strong fluorescence at 455 nm under the excitation of 330 nm. In the presence of ClO⁻, the fluorescence of NH₂-Cu-MOFs was quenched due to the electron transfer between NH₂-Cu-MOFs and ClO⁻. The NH₂-Cu-MOFs exhibited 87.6% fluorescence quenching efficiency with 12.5 μM ClO⁻ and the limit of detection is 0.036 μM. NH₂-Cu-MOFs exhibited the advantages of high sensitivity, high selectivity, and low response reaction time for ClO⁻ detection. This work developed a novel fluorescent probe for the detection of ClO⁻ and the NH₂-Cu-MOFs were successfully applied to analyse ClO⁻ in real water samples.