Postoperative depression significantly affects the quality of life of breast cancer patients. This study explores the potential therapeutic effects of esketamine on postoperative depression through modulation of the TREK-1 two-pore domain potassium channel. We analyzed data from 54 female breast cancer patients who underwent surgery at our hospital between 2019 and 2023, dividing them into experimental and control groups based on esketamine treatment. Transcriptomic sequencing of hippocampal neurons from rats identified potassium ion-related pathways and key regulatory genes, including TREK-1, influenced by esketamine. In vitro studies showed that esketamine primarily alleviates depressive symptoms by inhibiting TREK-1 protein expression, enhancing GABA neurotransmitter release, and improving neuronal activity, while overexpression of TREK-1 reversed these effects. Esketamine's inhibition of TREK-1 channels and promotion of hippocampal neuron activity effectively alleviate postoperative depression in breast cancer patients, suggesting a novel therapeutic strategy.