Around 15-25% of diabetes mellitus (DM) patients will develop diabetic foot ulcers (DFUs) with high morbidity, many studies have been proposed to search the most effective healing techniques.This study was conducted to demonstrate the ability of hyperbaric oxygen therapy (HBOT) as a complementary therapy in DFUs healing through raising vascular endothelial growth factor (VEGF) levels and suppressing tumour necrosis factor-alpha (TNF-α).All patients received the same treatment including wound debridement and wound care, but the patients in the HBOT group, breathed 100% oxygen at 2.4 ATA for 90 minutes in total of 20 sessions (four weeks).There were 32 diabetic patients with DFUs Wagner 3-4. VEGF levels after four weeks of HBOT was significantly elevated compared to the control group (p = 0.013). The effect size of VEGF levels was p = 0.005. TNF-α levels after four weeks of therapy were decreased (p = 0.01). Faster epithelialization is seen in the HBOT group (p < 0.001). We also performed path analysis, HBOT had a significant effect on the epithelialization (p < 0.001) and VEGF levels affected the epithelialization process (p = 0.042).HBOT administration leads to increased VEGF levels, decreased TNF-α levels, and accelerated wound healing of DFUs patients. HBOT directly aids epithelialization and indirectly through VEGF upsurge and TNF-α downturn.