Microplastics (MPs) and heavy metals (HMs) have emerged as significant environmental pollutants due to their persistence and potential risks to ecosystems, biodiversity and human health. In terrestrial soil systems, the combined presence of MPs and HMs can alter soil chemistry, reduce agricultural productivity and disrupt microbial communities. Despite increasing research on MPs in soil, significant knowledge gaps remain regarding their long-term interactions with HMs and their cumulative effects on agricultural ecosystems. This review critically examines the fate, transport mechanisms and coupled effects of MPs and HMs in soil environments, with a particular focus on agricultural systems. The study comprehensively summarizes the existing literature to address the following key aspects: (i) the fate and behavior of MPs and HMs in agricultural soil systems, (ii) transport mechanisms affecting their mobility and bioavailability, (iii) the interactive effects of MPs and HMs on soil health and ecology, and (iv) potential remediation strategies to mitigate their effects. The analysis shows that MPs significantly alter the adsorption-desorption dynamics of HMs, often increasing their mobility and bioavailability. Quantitative results suggest that MPs can enhance the leaching of HMs by up to 30–50%, thereby increasing their potential uptake by plants. In contrast to previous reviews, this study highlights the lack of empirical data on the interactions between MPs and HMs under real field conditions and argues for advanced monitoring techniques and mechanistic studies. Furthermore, the study emphasizes the need for sustainable prevention strategies, including improved waste management practices and biodegradable alternatives to conventional plastics. By identifying critical research gaps, this study aims to guide future investigations to develop holistic strategies and sustainable remediation approaches to mitigate the risks posed by MPs and HM in terrestrial ecosystems.