In this study, a hydrophilic adsorbent based on cyanopropyl-functionalized silica nanoparticles (CNPr@SiO2 NPs) was successfully synthesized via a sol–gel method. The nanoparticles were characterized using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, Brunauer–Emmett–Teller analysis, and thermogravimetric analysis. The synthesized CNPr@SiO2 NPs were then used as an adsorbent in dispersive micro-solid phase extraction (D-μ-SPE) of some polar and nonpolar organophosphorus pesticides from water samples prior to high-performance liquid chromatography-ultraviolet detection. Under the optimized parameters, the proposed method based on CNPr@SiO2 NPs showed low limits of detection in the range of 0.047–0.059 μg L–1, satisfactory recoveries (101.21%–109.12%), and good RSDs (0.20%–6.70%) for the extraction of OPPs from the various water samples. In addition, the developed D-μ-SPE method based on CNPr@SiO2 NPs showed a superior extraction capability toward the OPPs in comparison to commercial cyanopropyl-bonded silica solid-phase extraction cartridge. © 2020 Desalination Publications. All rights reserved.