This study investigated the effects of postharvest immersion treatment with different concentrations of VB₆ on the quality of pakchoi (Brassica rapa subsp. chinensis) stored at (15 ± 1) ℃. A comprehensive evaluation was conducted using grey relational analysis. The results demonstrated that 200 mg/L VB₆ treatment resulted in the lowest yellowing index and significantly delayed the decline in chlorophyll content. After 8 days of storage, the total chlorophyll content in this treatment group was 44.9% higher than that in the control group. This treatment effectively maintained the levels of antioxidants including ascorbic acid and total phenols (which were increased by 21.6% and 14.9% compared to the untreated control group, respectively), while significantly inhibiting the accumulation of malondialdehyde (MDA) and nitrite (which were decreased by 36.4% and 24.3%, respectively). Furthermore, it enhanced the activities of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), and increased the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and total reducing power. Grey relational analysis revealed that the 200 mg/L VB₆ treatment achieved the highest comprehensive score (0.776). It is confirmed that 200 mg/L VB₆ can delay the postharvest senescence of pakchoi through multiple physiological pathways, which provides theoretical support for the development of novel preservation technologies.