<p>To address environmental and health challenges while promoting sustainable clean water and soil, a highly sensitive graphite paste sensor incorporating a nanocomposite material has been developed. This sensor utilizes a yolk-shell (Ce/Fe) terephthalate (Ce/Fe-Tph.) framework intercalated with organoclay (MMt_D2000) nanolayers, forming a Ce/Fe-Tph./MMt_D2000 framework nanocomposite for the detection of arsenite (As³⁺)&#xa0;ions. The yolk-shell Ce/Fe-Tph./MMt_D2000 framework nanocomposite was synthesized via a solvothermal method, yielding excellent crystallinity and a high surface area of 1054&#xa0;m².g^−&#xa0;¹. This enhanced surface area provides abundant active sites, thereby improving sensor performance and supporting sustainable environmental monitoring. The 1.0% (Ce/Fe-Tph./MMt_D2000) modified graphite paste sensor (MGPS) exhibited enhanced electrocatalytic activity and adsorption performance. It achieved a broad detection range of 0.0015–0.0749 ppb (0.02–1.0 nM) and an ultralow detection limit of 0.00045 ppb (0.006 nM) for As³⁺ ions using square wave adsorptive cathodic stripping voltammetry (SW-AdCSV), with a sensitivity of 436.68 µA/ppb (32.7 µA.nM^− 1). The sensor also demonstrated high accuracy, reproducibility, and stability, along with exceptional selectivity for the detection of As³⁺&#xa0;ions in the presence of other heavy metal ions, without interference in strongly basic media. This sensor provides a simple, direct method for detecting As³⁺&#xa0;ions in environmental samples including real water and soil matrices, without requiring sample pretreatment. Its capabilities align with sustainable development goals by advancing environmental monitoring.</p> Graphical Abstract <p></p>