Cyanobacterial blooms represent one of the most complex microbial phenomena in aquatic ecosystems primarily determined by nutrient eutrophication (over-enrichment). At the molecular level, eutrophication, characterized by elevated phosphorus and nitrogen concentrations, activates key regulatory pathways in cyanobacteria, including genes related to nutrient uptake, nitrogen fixation (e.g., nifH), carbon assimilation, and toxin production like mcy, cyr, sxt gene clusters. These molecular responses enable rapid cellular proliferation under favorable environmental conditions such as high light intensity, warm temperatures, and particularly alkaline pH levels that often exceed 8.5 during bloom events due to intense photosynthetic activity and CO₂ depletion. The phylum Cyanobacteria comprises approximately 2700 species, classified into around 150 genera, such as Microcystis, Dolichospermum (Anabaena), Planktothrix, Aphanizomenon, and Nodularia. Metagenomic and single-cell sequencing shows that the true diversity is significantly underrated, with numerous of cryptic or uncultured species influencing bloom dynamics worldwide. These blooms are not cyanobacterial monocultures but complex consortia where cyanobacteria interact intricately with heterotrophic bacteria, viruses, archaea, and fungi. Mutualistic interactions facilitate bloom persistence and nutrient exchange, while antagonistic relationships, including viral lysis (via cyanophages) and bacterial allelopathy, may contribute to bloom senescence. Cyanotoxins (cyanobacterial toxins) such as anatoxinsmicrocystins and cylindrospermopsins can cause neurotoxic, hepatotoxic, and dermatotoxic effects in humans and animals. Treatment involves toxin adsorption, advanced filtration, and in some cases, medical detoxification. These methods are indeed reactive measures. Future bloom prevention strategies should be proactive and integrative, such as reducing nutrient loading through agricultural and wastewater reforms, deploying microbial biocontrol agents (e.g., algicidal bacteria), and employing synthetic biology to engineer microbial communities that suppress bloom-forming species.