<p>Pesticides and microplastics (MPs) are contaminants that coexist in agricultural soils; however, little is known about pesticide dynamics in the presence of MPs. Therefore, this study aimed to investigate the environmental behavior of ¹⁴C-diflubenzuron, ¹⁴C-fluazinam, and ¹⁴C-metribuzin under the influence of MPs in a tropical soil. The results showed that, at MPs concentrations of 1 and 4%, the sorption of ¹⁴C-metribuzin in soil was reduced by 40.79% and 51.12%, respectively. For ¹⁴C-diflubenzuron, 4% MPs addition led to a 20.65% reduction in sorption. For ¹⁴C-fluazinam, no interference in environmental behavior was observed. Desorption occurred for all pesticides. In solution, averages of 11% of ¹⁴C-metribuzin, 71% of ¹⁴C-diflubenzuron, and 68% of ¹⁴C-fluazinam were sorbed by MPs. In the same order, 36–93%, 2–2.8%, and 0.51–0.57% of ¹⁴C-metribuzin, ¹⁴C-diflubenzuron, and ¹⁴C-fluazinam were leached. A reduction in the mobility of ¹⁴C-metribuzin was observed, shifting from intermediate mobility to slightly mobile. Meanwhile, ¹⁴C-diflubenzuron and ¹⁴C-fluazinam remained immobile in soil. The results demonstrate that adding different concentrations of MPs to soil alters the environmental behavior of pesticides, depending on particle concentration, physicochemical properties, and pesticide dosage. This study provides insights into the interactions between MPs and pesticides and highlights the role of MPs as vectors of organic contaminants in soil. In addition, these findings suggest that MPs may influence pesticide retention, mobility, and leaching in tropical agricultural soils, with potential implications for groundwater contamination and environmental risk assessment.</p>