Purpose <p>Green tea-extract-mediated diatomite-supported zero-valent iron nanocomposites (nFe⁰-GT@DE) present a novel approach for remediating cadmium (Cd)-contaminated agricultural soils. Therefore, it is essential to evaluate their effects on soil quality and crop production to ensure sustainable and widespread application.</p> Methods <p>nFe⁰-GT@DE was applied to soil contaminated with a pronounced toxicity gradient of Cd (0, 0.60, 5.00, and 10.00&#xa0;mg kg⁻¹) across the entire growth cycle of wheat (170 days). The dynamically changes of Cd content in wheat and Cd fraction in soil were measured for investigating the Cd transformation and translocation in soil–wheat system. Furthermore, critical wheat physiological parameters and soil properties were determined to evaluate the ecotoxicity of Cd.</p> Results and discussion <p>The 170 days’ dynamically evaluate showed that soil acid-soluble Cd fraction decreased by up to 68.2%, while reducible, oxidizable, and residual Cd fractions increased by 13.5%, 11.3%, and 13.4%, respectively, from 105 days to 170 days. Correspondingly, Cd accumulation in wheat tissues was markedly inhibited throughout all fertility stages, resulting in a 69.9–78.5% and 59.4–81.6% reduction of Cd concentrations in wheat grain at 155 days and 170 days, respectively. nFe⁰-GT@DE effectively immobilized Cd through multiple mechanisms, including diatomite adsorption, Fe(hydroxide) oxide complexation, polyphenolic binding, and Fe⁰-mediated reduction.</p> Conclusions <p>The eco-friendly nFe⁰-GT@DE combined with polyphenolic compounds from tea extracts, significantly reduced soil Cd bioavailability, enhanced soil enzyme activity, and alleviated oxidative stress in wheat. Our results indicate that nFe⁰-GT@DE can provide a practical strategy for in situ remediation of Cd-contaminated soils while mitigating Cd transfer to crops, offering insights for sustainable agricultural management.</p> Graphical abstract <p></p>