Despite covering only ~1% of Earth’s surface, coral reefs support immense biodiversity and provide critical ecosystem services to over 500 million people globally. These reefs, primarily located in six tropical nations, face escalating threats from both local and global pressures, notably plastic pollution. Microplastics (MPs), in particular, are increasingly linked to coral disease, physiological stress, and ecological disruption. Recent studies estimate over 11.1 billion large plastic fragments are embedded in coral reefs, potentially rising by 40% by 2025. MPs serve as vectors for harmful pathogens and toxic substances, exacerbating coral vulnerability and reef degradation. While field and laboratory studies have expanded, knowledge on the environmental mechanisms and full impacts of MPs on coral systems remains limited. This chapter explores global MP distribution in reefs, ecological impacts, underlying mechanisms, and proposes policy interventions to mitigate plastic contamination in these vital marine ecosystems.