Plastic contamination has become a defining environmental challenge of the Anthropocene, permeating terrestrial, freshwater, and marine ecosystems with far-reaching consequences for biodiversity, human health, and sustainability. Despite growing recognition of its global and transboundary nature, efforts to monitor and mitigate plastic pollution remain fragmented due to weak governance and uneven technological capacity. This chapter explores how scientific innovation and international coordination can jointly strengthen global plastic monitoring systems. Emerging tools such as bioindicators, remote sensing, artificial intelligence, and nanotechnology-enabled sensors are transforming the detection and assessment of plastic contamination. However, their effectiveness depends on harmonized methodologies, open databases, and inclusive participation under global policy frameworks such as the forthcoming Global Plastics Treaty. The chapter proposes a roadmap toward a Global Plastics Observatory that integrates innovation, equity, and governance to achieve the Sustainable Development Goals (SDGs). By linking technology, policy, and justice, it argues for a unified, science-driven monitoring architecture to address plastic pollution at planetary scale.