This meta-analysis investigates the application of nanoparticles (NPs) for wastewater treatment in Iraq between 2010 and 2025. A total of 30 primary studies were included, covering the period 2010–2025, with more than 70% focusing on heavy metal removal using TiO₂ and ZnO nanoparticles. Various types of nanoparticles such as TiO₂, ZnO, AgNPs, and nZVI were evaluated for their effectiveness in removing specific contaminants, including heavy metals and organic pollutants. A comprehensive literature search was carried out using databases such as Scopus, PubMed, Web of Science, and Google Scholar. Extracted data included NP type, pollutant category, removal efficiency, and operational parameters. Results indicate that several nanoparticle systems achieved over 90% removal efficiency under optimised conditions. This study provides quantitative insights into the current state of nanoparticle-based water treatment in Iraq and highlights the most promising materials and applications. These findings contribute to a better understanding of nanotechnology’s role in addressing Iraq’s water pollution challenges and offer evidence-based direction for future research and implementation.