Objective Chronic stress can induce cognitive dysfunction, but the underlying mechanisms remain unknown. Studies have confirmed that the high mobility group box 1/Toll-like receptor 4 (HMGB1/TLR4) pathway is closely associated with cognitive impairment. Therefore, this research aimed to explore whether the HMGB1/TLR4 pathway involves in chronic stress-induced cognitive dysfunction.Methods The chronic unpredictable mild stress (CUMS) mouse model was established by randomly giving different types of stress every day for four consecutive weeks. Cognitive function was detected by novel object recognition test, Y-maze test, and Morris water maze test. The protein expressions of HMGB1, TLR4, B-cell lymphoma 2 (BCL2), and BCL2 associated X (BAX) were determined by Western blot. The damage of neurons in the hippocampal CA1 region was observed by hematoxylin-eosin (HE) staining.Results The protein expressions of HMGB1 and TLR4 were significantly increased in the hippocampus of chronic stress mice. Furthermore, inhibition of the HMGB1/TLR4 pathway induced by ethyl pyruvate (EP, a specific inhibitor of HMGB1) and TAK242 (a selective inhibitor of TLR4) treatment attenuated cognitive impairment in chronic stress mice, according to the novel object recognition test, Y-maze test, and Morris water maze test. In addition, administration of EP and TAK242 also mitigated the increase of apoptosis in the hippocampus of chronic stress mice.Conclusion These results indicate that the hippocampal HMGB1/TLR4 pathway contributes to chronic stress-induced apoptosis and cognitive dysfunction.