<p>A novel integrated method combining nanoconfined liquid phase nanoextraction (NLPNE) based on aminated carbon nanofibers/ carbon fibers (NH₂-CNFs/CFs) with pyrolysis-gas chromatography-mass spectrometry (Py/GC-MS) was developed for the sensitive determination of polystyrene (PS) nanoplastics in aqueous samples. The nanoconfined space constructed by intertwined CNFs accelerates the mass transfer of PS nanoplastics via short-range diffusion. Meanwhile, amino groups on the material surfacenot only generate electrostatic attraction with negatively charged PS nanoplastics, driving PS nanoplastics in water to migrate into the confined space loaded with nanoconfined solvent, but also endow the material with positive charges to interact with polar nanoconfined solvent. This effectively enhances the binding force between the solvent and the material surface and thus improves the extraction efficiency. Using acetonitrile as the optimized nanoconfined solvent, the proposed method achieves rapid extraction equilibrium, obeying pseudo-first-order kinetics and Langmuir monolayer adsorption model. Direct Py-GC/MS analysis employing styrene trimer (m/z 312) as the characteristic marker delivers a low limit of detection of 0.56&#xa0;µg/L. This method provided a novel technical solution for the detection of nanoplastics and supports future research on their environmental behaviors.</p> Graphical Abstracts <p></p>