High temperature (HT) shock is one of environmental stressors suppressing microalgal activities in microalgal wastewater bioremediation system. However, its inhibition mechanism and how to alleviate such suppression remain inadequately understood. This study confirmed a transient ferroptosis as a novel form of programmed cell death in a wastewater-indigenous Chlorella sp., responding to a 30-minute HT (50 °C) exposure, through the systematically physiological, metabolomic and transcriptomic analysis. Specifically, the HT-induced ferroptosis could be supported by both the growth and physiological indicators. These include the suppressed growth (76.05 %), suppressed nutrient removals (NH4+-N by 76.22 %, PO43--P by 64.15 %), accumulated intracellular Fe3+ concentrations (7.75-fold), enhanced oxidative stress (e.g., increased levels of reactive oxygen species (159.97 %)), activated antioxidant defense system (e.g., increased activities of superoxide dismutase (24.83 %) and catalase (5.03-fold)), and obvious membrane damage (e.g., increased levels of malondialdehyde (1.67-fold)). Further metabolomic analysis indicated that such HT-induced ferroptosis was also largely related to the significant alternations of lipid remodeling in three aspects: varied abundance of certain lipids specific to chloroplast membrane or mitochondria, accumulation of certain lipids with lower unsaturation, and formation of lipid peroxides disrupting membrane integrity. Moreover, the key genes involved in ferroptosis correspondingly responded, especially those associated with lipid metabolism (e.g., ACSL), antioxidant defense system (e.g., GSS, GPX and GSR), mitochondrial normal functioning (e.g., SEL1L), autophagy regulation (e.g., ATG9, ATG11, ATG13) and protein folding (e.g., HSPA5, HSPA1s, HSP90B). In addition, the supplementation of the typical ferroptosis inhibitor Ferrostatin-1 effectively mitigated lipid peroxide accumulation and suppressed the onset of ferroptosis, accelerating subsequent recovery of NH4+-N removal by 60.66 %. These findings update current understandings of microalgal ferroptosis-like inhibition, offering Ferrostatin-1 supplementation as a potential strategy for system resistance to heat stress in microalgae-based bioremediation system.