To understand the changes in the peroxiredoxin-2 (PRDX2) expression level in the wound margin tissue (T-PRDX2) of patients with diabetic foot ulcer (DFU) before and after negative pressure wound therapy (NPWT). Additionally, the study aimed to explore the association between PRDX2 expression and the treatment outcome of DFUs to provide a new theoretical basis for revealing the mechanism of NPWT promoting the healing of DFUs. Fifty-six type 2 diabetes patients with foot ulcers undergoing NPWT (the DFU group) and 28 patients with chronic lower limb skin ulcers with normal glucose tolerance undergoing NPWT (the skin ulcer control [SUC] group) were included in the study. T-PRDX2 was detected using Western blotting, and the superoxide dismutase (SOD) activity and the malondialdehyde (MDA) and glutathione (GSH) levels were detected using a biochemical method. In addition, in vitro experiments were conducted to determine the effect of PRDX2 expression on normal human dermal fibroblast (NHDF) proliferation, migration, and apoptosis. Before NPWT, the DFU group exhibited a significantly lower T-PRDX2 expression level compared with the SUC group. After one week of NPWT, the T-PRDX2 expression level, SOD activity, and GSH content in the wound margin tissues of the DFU and SUC groups significantly increased compared with the before NPWT levels. Conversely, the inflammatory indicators (white blood cell, neutrophil percentage, C-reactive protein, and procalcitonin) and MDA content were significantly lower than the before NPWT levels. The expression changes of T-PRDX2 before and after NPWT in the DFU and SUC groups were positively correlated with the 4-week wound healing rate. In vitro experiments demonstrated that PRDX2 could alleviate the oxidative stress in NHDFs, thereby promoting their proliferation and migration, while reducing cell apoptosis. NPWT promotes DFU healing by increasing T-PRDX2, and changes in the T-PRDX2 might be associated with the therapeutic effect of NPWT.