<p>The increasing frequency of freeze-thaw (FT) events, combined with aluminum chloride (Al) contamination driven by global warming, poses significant stress on plant seedlings during early spring. While acetic acid has shown potential in enhancing tolerance to various abiotic stresses, its role in mitigating the combined effects of FT and Al stress remains underexplored. This study investigates the physiological effects of acetic acid on rye (<i>Secale cereale</i> L.) under these stresses. Results showed that Al stress increased reactive oxygen species and malondialdehyde, signaling enhanced membrane lipid peroxidation, while antioxidant enzyme activities like peroxidase and catalase were elevated as defense mechanisms. Al stress also reduced chlorophyll content, photosynthetic rates, and transpiration by interfering with magnesium uptake. Combined FT and Al stress further exacerbated these effects, leading to higher MDA, soluble protein, and soluble sugar levels. However, acetic acid effectively reduced these impacts by enhancing antioxidant enzyme activity and improving shoot growth, relative water content, photosynthetic pigments, and soluble sugars, indicating improved osmotic adjustment. Acetic acid also promoted stem and root biomass and enhanced cold tolerance, suggesting a protective role under stress conditions. These findings provide useful insights for managing abiotic stress in crops in cold and temperate regions, including Northeast China, continental and coastal regions of Canada, and Northern Europe, where seasonal freeze–thaw cycles and acidic soils associated with aluminum toxicity are prevalent. This may support the development of targeted strategies to reduce crop yield losses under such conditions.</p>