Glutathione-capped copper nanoclusters (CuNCs) are presented that display aggregation-induced emission (AIE). This feature was exploited for selective and sensitive quantification of creatinine (CRN) which is an important diagnostic parameter. In the presence of Al 3+ ions, such CuNCs rapidly aggregate, and this induces enhanced a red emission. The AIE nature of CuNCs was proven via TEM and fluorimetry. On addition of CRN, the coordination between CRN and Al 3+ ions led to the quenching of fluorescence due to weakening the AIE. The best fluorescence intensity was measured at excitation/emission peaks of 360/585 nm. Quenched fluorescence intensity showed a linear dependence on the concentrations of CRN in the range of 2.5–34 μgL −1 with a detection limit of 0.63 μgL −1 . The sensing mechanism of probe for CRN detection is discussed. The probe was applied to the determination of CRN in spiked human serum samples and gave satisfactory results. Graphical abstract Aluminum(III) ions trigger the aggregation-induced emission (AIE) in glutathione-capped copper nanoclusters (CuNCs). Introduction of creatinine leads to deaggregation of CuNC aggregates, and this is accompanied by the quenching of the luminescence. This phenomenon was exploited in an assay for creatinine.