MicroRNA-122 (miR-122) is a sensitive biomarker for paracetamol-induced liver injury. This study evaluated Dynamic Chemical Labelling (DCL) combined with a clinical laboratory assay to quantify miR-122 in human serum, as a proof-of-concept for hospital use. Serum was collected from 19 healthy individuals and 19 patients with paracetamol drug-induced liver injury (DILI). miR-122 was labelled with a biotinylated SMART-Base and quantified using a multiplex, bead-based, fluorescence detection system. Median miR-122 concentration was 233.4pg/ml in DILI patients vs. 15.2pg/ml in controls. Concentrations ranged from 17.5–1376.9pg/ml (DILI) and 2.2–67.2pg/ml (controls). The Mann-Whitney U test showed significant group differences (p < 0.0001). ROC analysis yielded an AUC of 0.96, with a 29.7pg/ml cut-off providing 92.6% sensitivity and 89.4% specificity. miR-122 moderately correlated with ALT (r=0.56, p=0.03). DCL with fluorescence detection is a promising clinical tool for miR-122 quantification.