Microplastics, or plastic particles smaller than 5 mm in size, have become ubiquitous in the environment, found in places ranging from remote deep ocean trenches to minute dust particulates. From the breakdown of larger plastic products and the release of synthetic clothing fibers, these particles enter the ecosystem and cycle through the various components including aquatic, terrestrial, and human systems. Due to their durability, capacity to adhere to other toxic compounds, and potential effects on humans and ecosystems, microplastics have recently risen to the forefront of environmental and health concerns. To address these critical issues, there has been a surge in research related to the microplastics cycle, examining where they originate, how and where they travel, and their environmental and human health impacts. Research on the microplastic cycle is often broken down into its various individual components such as sources, fate, and effect, and further scattered through the literature are focuses on specific environments such as land, oceans, and freshwater, as well as on human health. Here, we review the current state of the literature on the microplastic cycle across its various environmental reservoirs. In-depth examination of the microplastics cycle is necessary for understanding the scope of the problem and developing viable solutions or mitigation strategies, such as reducing plastic production and promoting recycling. Understanding the complex microplastics cycle is an urgent issue that necessitates multidisciplinary research and action.