This chapter examines the critical intersection of nanotechnology with environmental concerns through the lens of ecotoxicology and life cycle assessment. It begins with foundational concepts in nanoecotoxicology and advances through testing methodologies and standardized assays essential for evaluating nanomaterial impacts. Environmental interactions across diverse ecosystems are analyzed, followed by an exploration of life cycle assessment approaches for nanomaterials. The chapter also provides a comprehensive review of the regulatory landscape governing nanomaterial safety, including international frameworks and compliance challenges. Finally, it investigates how artificial intelligence and Internet of Things technologies are transforming ecotoxicological monitoring and assessment, enabling more sophisticated predictive modeling and real-time environmental surveillance. Throughout, the chapter underscores the imperative of balancing nanotechnological innovation with environmental stewardship to ensure sustainable development.