A fluorescent probe was fabricated for the determination of sparfloxacin. The nanocomposite probe was constructed by incorporating nitrogen-doped graphene quantum dots, zinc oxide decorated carbon foam and magnetite into a matrix formed from a molecularly imprinted polymer. The fabricated nanoprobe was characterized and the fabrication and determination conditions were optimized to obtain the highest sensitivity. The determination of sparfloxacin was based on the decreasing of emission response of the nanocomposite probe when the target analyte rebinds to the inherent recognition sites of the fluorescent probe. Under the best conditions, the quenching of fluorescence was linear in the range of 0.10–100.0 μg L−1 (R2 = 0.991) with the limit of detection being 0.10 μg L−1. The nanocomposite probe exhibited high specificity with an imprinting factor of 7.93. This optosensor was used to determine sparfloxacin in milk and good recoveries were observed ranging from 93.0 % to 100.8 % with RSDs lower than 5 %. The results also agreed with the results obtained using a chromatographic method but the developed method has higher sensitivity, at lower cost and faster determination procedure. In addition, the developed optosensor can be simply modified for highly selective determination of other trace levels of target compounds by changing the template with minor changes in determination conditions.