Microplastics are recognized as a global environmental crisis due to their increasing production, persistence and high mobility across ecosystems. They are continuously transported between terrestrial, aquatic and atmospheric systems through processes such as runoff, ocean currents and atmospheric deposition. This highlights global distribution of microplastics beyond their original sources. Beyond physical transport, microplastics act as active ecological substrates which supports the formation of distinct microbial communities referred to as plastisphere. The formation and structure of these communities are governed by both intrinsic polymer properties and extrinsic environmental factors, with early colonization driven by deterministic selection of generalist microorganism and later stages shaped by temporal succession and stochastic processes. In addition to their ecological role, microplastics act as vectors for a wide range of contaminants and microorganisms. Their surfaces can adsorb and transport heavy metals, persistent organic pollutants and antibiotics. This influences their mobility and bioavailability in the environment. These interactions raise concerns regarding their impacts on environmental and human health where microplastics enter biological systems through ingestion and inhalation and induce adverse effects. Despite increasing research, most studies address these aspects independently, which leads to fragmented understanding. This review provides an integrated understanding of microplastic by linking their transport pathways, plastisphere ecology and vector role, highlighting their impact on environmental and human health.