The presence of microplastics (MPs) in agricultural soils has reshaped pesticide environmental behavior. These particles act as additional phases in the soil matrix and influence sorption, desorption, transport, persistence, and bioavailability. The magnitude of these interactions depends on pesticide properties such as solubility, hydrophobicity, molecular weight, ionization constant, and partition coefficients, as well as MP characteristics. Interactions are mediated by van der Waals forces, hydrophobic partitioning, hydrogen bonding, electrostatic attraction, pore filling, and aromatic interactions. Aged MPs exhibit greater affinity due to increased polarity and surface heterogeneity. These processes modify pesticide distribution between soil phases, alter transport pathways, and influence persistence. Understanding these mechanisms requires analytical approaches to characterize MPs and quantify pesticides in complex matrices. Chromatographic, spectrometric, isotopic, thermal, and microscopic techniques are complementary, as no single method captures the full complexity of MP–pesticide interactions. Evidence from soil–plant systems indicates that MPs can reduce bioavailability, alter dissipation, interfere with microbial activity, and affect plant uptake, with implications for agronomic performance. However, limitations remain, including the use of standardized MPs, differences between artificial and natural aging, lack of methodological harmonization, and limited long-term and tropical studies. Environmentally realistic approaches are needed to better understand MPs as pesticide vectors.