Abstract: With the continuous input of microplastics into freshwater environments, their long-term coexistence with cyanobacterial blooms in eutrophic waters has led to the formation of a complex pollution system characterized by multiple interaction pathways. Based on existing domestic and international studies, this review systematically summarizes the research progress and interaction mechanisms between microplastics and cyanobacterial blooms from the perspectives of physiological responses, population behaviors, and ecological processes. The results indicate that microplastics can alter the physiological status and collective behavior of cyanobacteria through attachment, light shading, and chemical stress, thereby influencing bloom formation and cyanotoxin production. During bloom development and succession, cyanobacteria can in turn markedly alter the surface physicochemical properties, migration behavior, and environmental fate of microplastics via extracellular polymeric substance (EPS) secretion, biofilm formation, and heteroaggregation processes. The resulting microplastic-cyanobacteria heteroaggregates may further reshape particle sedimentation and transport dynamics, and amplify aquatic ecological risks at both population and ecosystem scales by enhancing bloom persistence, facilitating pollutant transfer within food webs, and disrupting biogeochemical cycling. These findings contribute to a more comprehensive understanding of microplastic-cyanobacteria interactions and their ecological effects, thereby providing a scientific basis for the risk assessment and management of complex pollution in eutrophic aquatic systems.