In this work, we introduce a novel procedure for the quantification of ibuprofen (IBU) even at very low concentrations. The approach involves a solid phase extraction of IBU in aqueous samples by using magnetic nanoparticles functionalized with nanomeric silver (Fe3O4@AgNPs), and its subsequent desorption using a microvolume of acid solution. Measurements were carried out by the means of a nanodrop system of ultraviolet spectrophotometry operating at 254 nm. For a volume of 30 mL of water containing IBU, 100 µL of a suspension of Fe3O4@AgNPs were employed to achieve a total adsorption of the analyte on the surface. The desorption was carried out by using 30 µL of a 0.1 N nitric acid solution, allowing us to reach an enrichment factor around 990. The use of a nanodrop spectrophotometric system allows obtaining a great sensitivity for the quantification of this species without having to resort to more sophisticated analytical techniques. Calibration graphs were obtained for IBU concentrations within the range 0.02–1.5 µL L−1. The results were corroborated with a certified reference material showing that this technique is valid for an exact quantification of IBU traces.