Microplastics (MPs) and nanoplastics (NPs) are emerging environmental contaminants with profound implications for food safety and human health. Their pervasive distribution in marine and freshwater ecosystems facilitates bioaccumulation and trophic transfer, ultimately leading to human exposure through seafood consumption, drinking water, and airborne inhalation. MPs exhibit complex interactions with biological systems, inducing oxidative stress, inflammatory responses, endocrine disruption, and metabolic disorders. Ingestion of MPs disrupts intestinal homeostasis, alters gut microbiota composition, and contributes to metabolic dysfunctions such as nonalcoholic fatty liver disease (NAFLD) and insulin resistance. Respiratory exposure induces lung inflammation, fibrosis, and compromised pulmonary function, while systemic translocation allows MPs to accumulate in the liver, cardiovascular system, and central nervous system, where they impair lipid metabolism, vascular integrity, and neurocognitive function. Endocrine and reproductive toxicity of MPs is attributed to their ability to adsorb persistent organic pollutants (POPs), heavy metals, and endocrine-disrupting chemicals (EDCs), leading to hormonal dysregulation and reproductive impairment. The detection of MPs in human tissues, including the placenta and brain, underscores their potential for transgenerational toxicity. Given the increasing global plastic burden, immediate regulatory interventions, advanced waste management strategies, and interdisciplinary research are imperative to mitigate MPs’ ecological and health risks and ensure sustainable environmental policies.