This study investigated the mechanism by which combined vacuum packaging and 0.5% (w/v) ascorbic acid treatment (VP-AsA) preserves fresh-cut potatoes at 4 °C, integrating physiological and transcriptomic analyses. Transcriptome sequencing revealed 2246 differentially expressed genes (DEGs) in the VP-AsA group. Notably, key genes involved in glutathione metabolism and NADPH regeneration—encoding glutathione reductase (GR), glutathione S-transferase (GST), isocitrate dehydrogenase (IDH), glucose-6-phosphate dehydrogenase (G6PDH), and ornithine decarboxylase (ODC)—were significantly up-regulated. This transcriptional reprogramming, which was associated with increased glutathione (GSH) content, provides a molecular basis for the enhanced antioxidant capacity observed in the treated samples, including elevated superoxide dismutase (SOD) activity, DPPH/ABTS radical scavenging capacity, and ferric reducing antioxidant power (FRAP). Concurrently, VP-AsA treatment reduced water migration, inhibited polyphenol oxidase (PPO) and peroxidase (POD) activities, and maintained key textural properties (hardness, fracturability, springiness, chewiness) during the first 9 days of storage. These results suggest that VP-AsA treatment preserves quality at least in part by transcriptionally activating glutathione-mediated antioxidant pathways, providing insights for fresh-cut fruits and vegetables quality control.