<p>Harmful algal blooms (HABs) are one of such unprecedented issues that significantly disturb both freshwater and seawater and have posed a severe risk to human health, ecological security, and socio-economic growth. The present review primarily emphases on the significant development on the extenuation of HABs using photocatalytic nano-architectonics. The sources and types of numerous algal toxins, their ecological influences, and health risk assessment are discussed. Further, the potential of various advanced functional photocatalytic nano-architectonics such as MOFs, TiO₂-based metal composites, carbon nitrides, COFs, graphene-based materials, zeolitic imidazolate frameworks, porous coordination networks, hybrid composite materials involving self-assembled metal ions/clusters with bridging organic ligands, biochar, etc., for HABs inhibition is explored. Furthermore, the plausible mechanisms of photocatalysts for the obliteration of HAB cells, along with numerous factors affecting the photocatalytic algal inactivation, are also covered. Finally, the review summarizes the discussion on the limitations, challenges, future perspectives, and solutions for further research in this research area.</p> Graphical abstract <p></p>