Microplastics (MPs) pollution has become a pressing environmental issue, significantly impacting marine ecosystems and food safety. These synthetic particles, defined as plastic fragments smaller than 5 mm, originate from various sources and have infiltrated marine habitats worldwide, from surface waters to deep-sea sediments. This review provides a comprehensive analysis of MPs contamination in marine organisms, highlighting global case studies and detection methodologies. MPs are ingested by marine life through direct uptake or trophic transfer, causing adverse biological effects, including growth inhibition, reproductive impairments, and bioaccumulation of toxic substances. Humans are exposed to MPs primarily through seafood consumption, raising concerns about potential health risks. We examine various detection techniques, including visual identification, spectroscopic methods (FTIR, Raman spectroscopy), and thermal analytical approaches (Py-GC/MS, TGA), evaluating their advantages and limitations. Despite significant research progress, challenges remain, particularly in detecting nanoplastics, standardizing methodologies, and understanding the long-term ecological and human health implications. Case studies from different regions demonstrate varying contamination levels, influenced by local environmental conditions, industrial activities, and waste management practices. This review emphasizes the need for improved monitoring, regulatory frameworks, and mitigation strategies to address the pervasive threat of MPs pollution. Future research should focus on refining detection technologies, assessing human health impacts, and implementing policy measures to reduce plastic emissions into marine environments.