The widespread use of synthetic polymers has reshaped modern life but has also driven an accelerating environmental crisis. This chapter traces the complete life cycle of plastics, emphasizing the post-consumer phase of plastics and the role of household plastic waste as a key contributor to micro-nanoplastics (MNPs) pollution. It explores the physicochemical transformations and release pathways of plastics under typical domestic conditions, with a focus on their fate in terrestrial and aquatic environments. Factors influencing their mobility and persistence in soil, water, plants, and fauna were explored, alongside sector-wise contributions from packaging, textiles, and consumer goods. Municipal solid waste (MSW) acts as a primary source of plastic pollution in the environment if not treated properly, with comparative assessments from Europe, the USA, and India revealing significant regulatory and infrastructural disparities. While developed nations address legacy contamination, rapidly industrializing regions face mounting consumption and inadequate waste systems, exacerbating pollution risks. To mitigate this, the chapter evaluates the efficacy of affordable, accessible engineered biochar derived from organic residues for remediating plastic and its co-contaminants. Column and batch sorption experiments are required to optimize and remediate MNPs due to biochar’s strong affinities for various plastic polymers. The findings highlight the promise of biochar in decentralized plastic waste management and its role in advancing circular, sustainable remediation strategies.