A green, fast, and economical technique for the manufacture of N,S-CQDS has been devised based on 3-min microwave irradiation of citric acid and thiosemicarbazide that furnished highly fluorescent quantum dots (λex/em of 360/430 nm) with high water solubility and stability. Transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), Zeta potential analysis, Fourier transform infrared, UV-Visible spectroscopy, and fluorescence spectroscopy were used to fully characterize the N,S-CQDS. The obtained N,S-CQDS are spherical shaped with average size of 13.2 ± 4.3 nm and Zeta potential of -32.46 ± 1.55 mv. The effect of UV light and pH on the fluorescence intensity of the synthesized N,S-CQDS were also investigated. The synthesized N,S-CQDS were used as a fluorescent nanoprobe for the determination of two 5-nitroimidazole antimicrobials; secnidazole (SNZ) and tinidazole (TNZ) by fluorescence turn-off via inner filter effect and static quenching mechanisms. This approach demonstrated a linear dependency of the fluorescence signal on the concentration of both drugs over the range of 15-200 μM. The limit of detection and limit of quantification were 2.18 and 6.62 μM, respectively, for SNZ, and 2.29 and 6.96 μM, respectively, for TNZ. The developed method was used to determine both drugs in pharmaceutical dosage forms and human urine samples with % recovery of 100.65 ± 1.35 for SNZ, 98.66 ± 0.47 for TNZ in pharmaceutical dosage forms and 102.24 ± 2.93 for SNZ, 98.2 ± 1.78 for TNZ in case of spiked human urine samples. The approach's selectivity was confirmed for determining both analytes in the presence of various co-existing and co-administered species. The method validity was assessed in accordance with ICH recommendations. Various metrics were used to evaluate the greenness of the proposed probe. The developed probe is environmentally-friendly due to the quick synthesis of luminous N,S-CQDS using affordable and low-energy microwave radiation, and the absence of organic solvents.