Microplastics (MPs) are emerging pollutants, which have been widely distributed in aquatic environments where they interact and disturb the content of dissolved organic matter (DOM). DOM is produced in fresh water environments as a result of the decomposition of aquatic organisms and plant litter with the help of microbial activities. It plays a prime role in greenhouse gas emissions and the carbon cycle in freshwater environments. Also, aquatic DOM with large molecular weight has a great influence on the high-level microbial diversity. The affinity of MPs toward DOM is very high, and their assimilation depends on the hydrological conditions, type of DOM, and MP properties. As a result, the presence of DOM in sediments is reduced. DOM in freshwater may also be involved in the bioavailability and migration of MPs in aquatic environments. Microbes that are present in DOM in water adjust their metabolic patterns and reduce the stress of MPs, but the effect of MPs will be pronounced in combination with heat waves. Biodegradation of MPs releases DOM into the environment. That MP-derived DOM increases the diversity and abundance of the microbial community. The focus of this chapter is to explore the occurrence of DOM in freshwater ecosystems, their interaction with MPs, and the various detrimental effects that different types of DOM can have on MPs.