One of the environmental problems of most concern to citizens, governments, and scientists is the increasing contamination caused by synthetic plastics; in recent years, there has been a rising awareness concerning microplastics and nanoplastics manufactured and generated through physicochemical and biological degradation processes. This dimension promotes interaction with biological entities and enhances their mobility through air, soil, and water bodies, where they can interact with several pollutants. These pollutants have the potential to adsorb, transport, concentrate, and desorb from the surface of micro/nanoplastics, generating co-contamination processes more widespread than their macroscopic counterparts, which have exhibited synergistic and antagonistic effects on the organisms with which they can interact and/or internalize, being this a research field of great interest and development at present. To provide a comprehensive understanding of the relationship between chemical pollutants and micro/nanoplastics, this chapter is organized around three main themes: the sorption behavior of micro/nanoplastics and the factors that influence this interaction, the diverse types of chemical pollutants that can be adsorbed in micro/nanoplastics, and the environmental impact of these interactions in soil, air, and water bodies, with a particular focus on marine and coastal ecosystems.