Diagnosis and treatment of male infertility present persistent clinical challenges, with etiologies spanning genetic anomalies, endocrine disturbances, genital tract infections, varicocele, lifestyle factors, and environmental exposures. Among these, exposure to environmental contaminants is increasingly recognized as a critical contributor to male reproductive impairment and declining sperm quality. Micro- and nanoplastics (MNPs), as ubiquitous emerging environmental pollutants, can enter the human body via three primary routes: gastrointestinal ingestion, respiratory inhalation, and dermal contact. Upon internalization, MNPs trigger male reproductive toxicity through diverse molecular pathways, including the induction of oxidative stress, DNA damage, disruption of sex hormone secretion, energy metabolism dysfunction, gut microbiota dysbiosis, ferroptosis, and aberrant autophagy. Cumulative evidence suggests that these mechanisms may act in concert to compromise sperm quality and male fertility; furthermore, such exposure has been associated with an elevated risk of developmental abnormalities in offspring in certain experimental models. In this review, we systematically elucidate the mechanisms linking MNP exposure to the pathogenesis and progression of male infertility. We also aim to offer novel insights for the clinical diagnosis and management of male infertility, provide theoretical references for preconception care and reproductive health, and establish a scientific foundation for advancing targeted prevention and control strategies against MNP pollution.