Industrialisation, urbanisation and technological advancement have profoundly transformed Earth’s natural systems, particularly impacting marine ecosystems. While these developments have propelled human progress, they have also introduced persistent pollutants that threaten ecological balance and disrupt biogeochemical cycles. This chapter focuses on three key pollutant classes: heavy metals (HMs), organic contaminants (OCs) and microplastics (MPs) originating largely from anthropogenic sources. HMs such as mercury, lead and cadmium enter marine environments via industrial discharge, atmospheric deposition and agricultural runoff, accumulating in sediments and biomagnifying through food webs. OCs, including persistent organic pollutants (POPs), polycyclic aromatic hydrocarbons (PAHs) and chlorinated pesticides, are toxic, lipophilic and environmentally persistent. MPs, both primary and secondary, have emerged as ubiquitous pollutants affecting marine organisms through ingestion, chemical leaching and acting as vectors for other contaminants. Increasing evidence reveals complex interactions among HMs, OCs and MPs, posing challenges for risk assessment and monitoring. These multifaceted dynamics underscore the need for an integrated research approach bridging environmental chemistry, ecotoxicology and marine ecology. As human pressures on ocean systems and the blue economy grow, advancing our understanding of pollutant interactions is essential for protecting marine biodiversity and ensuring the long-term resilience of ocean ecosystems vital to human well-being.