<p>Neuroblastoma is a paediatric malignant cancer that affects immature nerve cells and is most commonly prevalent in infants and young children. It often occurs in adrenal glands and peripheral nerve tissues. Since its symptoms are hardly expressed and vary with tumour size, the need for early and non-invasive diagnostic approaches is vital. Homovanillic acid (HVA) in urine is considered as key biomarker for early detection of neuroblastoma. In this study, we have developed a lanthanide-based luminescent probe based on Eu-citrate complex (Eu-cit), whose red fluorescence is quenched by Fe²⁺ and subsequently restored in the presence of HVA. The system (Eu-cit@Fe) demonstrates high selectivity and sensitivity towards HVA, with a detection limit of 0.45&#xa0;µM and performs effectively in spiked human serum and urine samples with satisfactory recovery rates (86–105% and 90–104%). Furthermore, a simple paper strip assay was fabricated for practical applications. Compared with traditional methods, the designed probe provides a specific, non-invasive and rapid method for HVA detection and potentially paves way for early-stage diagnosis and monitoring of neuroblastoma.</p> Graphical abstract <p></p>