Zinc oxide nanoparticles (ZnO-NPs) were fabricated using carbon quantum dots (CQD) solution using a laser ablation technique to investigate the photoluminescence properties and applications for the interaction of mercury and lead ions. The ablation times were 5, 7, 10, and 13 min. The prepared samples were characterized using UV–visible spectroscopy, Fourier transform infrared spectroscopy, and high-resolution transmission electron microscopy, which verified the formation of ZnO-NPs in the CQD solution and the capping of the spherical nanoparticles by the functional group of the CQD. Spherical ZnO-NPs were formed in the CQD solution with a particle size in the range of 7.5 to 14.03 nm. The prepared samples were then used to detect mercury and lead ions in aqueous solution using photoluminescence spectroscopy. The photoluminescence peak shift in the presence of mercury was greater than that in the presence of lead. Thus, the interaction of zinc oxide–nanoparticles/CQD with mercury is stronger than that of the CQD with lead.