The Yangtze River Basin experienced long-term drought and extreme warming in 2022, which substantially affected the water quality, aquatic ecosystem in lakes, and altered the dynamics of algae. By now, little research has focused on the impact of drought events on cyanobacterial blooms. This study analyzed the characteristics of cyanobacterial blooms and the key drivers in Lake Taihu in 2022, based on the long-term monitoring data (2005-2022) of nutrient and chlorophyll-a (Chl.a) concentrations in the lake, combined with the cyanobacteria bloom area interpreted from remote sensing images. The results showed that the average area and maximum area of cyanobacteria bloom in Lake Taihu decreased significantly in 2022 during the bloom season (May to September), with the bloom area in May only occupying 20% of the average of the past five years. The concentration of Chl.a and Microcystis biomass obtained by water sample collection also showed a downward trend in May. For nutrients, the average total nitrogen and total phosphorus were 1.41 mg/L and 0.084 mg/L, respectively, in Lake Taihu in 2022, which decreased by 30.6% and 27.3% compared with the average of the past five years, and the lowest values since 2005. The results of kriging interpolation revealed that in February, the majority of lake areas exhibited low concentrations of dissolved nitrogen and phosphorus, except for the estuarine region of Zhushan Bay. Specifically, in 79% of the lake area, the total dissolved phosphorus concentration was less than 0.02 mg/L. The random forest analysis showed that total phosphorus, water temperature, and wind speed were the key factors that influenced the biomass of Microcystis and algae in May. The decline of phosphorus levels and inadequate external loading during the spring season resulted in low concentrations of phosphorus spread widely across the lake, which restricted the growth of Microcystis in 2022 spring. Additionally, in the context of extremely high temperatures in summer, the cyanobacterial blooms had not expanded significantly, which was attributed to the reduction of external loading due to the extreme drought maintained the low nutrients in most regions of the lake. The results showed that the sensitivity of algal biomass to nutrient dynamics had emerged in a large area of Lake Taihu and highlighted the regulating role of external loading. It is crucial for controlling the bloom intensity under the changeable climates in the future through persistently reducing the external input, paying attention to the internal loading, and regulating the ecosystem structure in the lake.