Harmful algal blooms (HABs) refer to uncontrolled and rapid growths of algae or cyanobacteria in aquatic and marine ecosystems, frequently settling at or near the water surface. These microorganisms are incredibly resilient and tolerant, enabling them to grow under diverse environmental conditions. Their capacity to maximize physiological as well as ecological performance as a response to abiotic conditions is evidence of their competitive supremacy in aquatic environments. Recent years have seen a growth in the prevalence and intensity of HABs, leading scientists and policymakers to advance monitoring and mitigation measures. Remote sensing devices like satellite-based systems (e.g., NASA’s MODIS) allow for large-scale observation of bloom dynamics through chlorophyll concentration and thermal pattern detection. At the same time, in situ sensors give continuous information on water quality parameters such as temperature, nutrient levels, and toxin concentrations, which are synthesized into early warning systems using predictive models. Preventative action aims at minimizing anthropogenic sources of eutrophication by limiting agricultural runoff, enhancing wastewater treatment, and recreating natural filtration mechanisms such as wetlands. We covered in this chapter emerging control methods such as ultrasonic disruption and clay flocculation are designed to prevent the formation of blooms prior to the development of ecological and public health effects. Knowledge of the adaptive mechanisms of bloom-forming species is essential to further improve predictive models and implement more successful management strategies. Since HABs continue to present challenges to aquatic biodiversity, water resources, and human health, interdisciplinary studies and advanced technologies must continue being necessary in order to curb their spread in a changing climate. Future research must focus on sustainable means that tackle both the ecological causes of HABs and their socioeconomic impacts.