Chlorophenols (CPs) are widespread environmental contaminants with mutagenic, carcinogenic, and teratogenic properties. Their biodegradability is limited by the presence of strongly electronegative chloride ions, prompting the use of biostimulation strategies to enhance degradation. However, there is still a gap in the investigation of the mechanisms of the effect of different biostimulants. The current study investigates the effects of polymerized ferric sulfate (PFS), fulvic acid (FA), and extracellular microalgal metabolites (EMA) on stimulating 2-chlorophenol (2-CP) degradation by Acinetobacter sp. strain ZY1 and elucidates the underlying mechanisms. Results indicate that the addition of these biostimulants increased 2-CP degradation efficiency by 21.5–46.7 %. Physiological analysis revealed that biostimulants restored ZY1 morphology under 2-CP stress, reduced reactive oxygen species (ROS) release, and mitigated membrane damage. PFS addition led to a 2.1-fold increase in EPS-PN secretion. Transcriptomic analysis showed upregulation of genes related to membrane composition, transmembrane transport, metabolism, and cell proliferation. Enhanced 2-CP degradation resulted from accelerated bacterial metabolism and proliferation, resistance to 2-CP stress, and increased activity of degrading enzymes like oxygenase and hydrolase. These findings provide a theoretical basis for chlorophenol removal via biostimulation at physiological and molecular levels.