Oxidative stress injury is a critical complication during long-term extracorporeal membrane oxygenation (ECMO) support and is further aggravated in critically ill patients with diabetic metabolic comorbidities. Nevertheless, conventional ECMO gas exchange membranes only focus on passive physical gas transport and lack active antioxidant regulatory functions, which limits their ability to alleviate ECMO-related oxidative damage. Herein, a multifunctional PVDF-HFP composite membrane was fabricated using α-lipoic acid (LA) as a dual-functional modifier serving as both a natural antioxidant and a pore-forming agent. A solvent evaporation-induced phase separation (EIPS) strategy was adopted to construct tunable multiscale porous architectures. The optimized PHL2 membrane exhibits prominently enhanced CO₂/O₂ permeability (CO₂: 93.7 ± 7.3 Barrer, O₂: 87.0 ± 3.8 Barrer), low surface energy, favorable hydrophobicity/blood-repellency, and excellent free radical scavenging performance (maximum ABTS clearance of 85.6%). The PHL membrane possesses reliable mechanical durability, superior hemocompatibility, and cytoprotective effects against high concentrations of glucose and H₂O₂-induced oxidative injury. In simulated ECMO circulation tests, the PHL2 membrane achieves rapid and stable blood oxygenation (SaO₂ > 95% within 15 min). More importantly, the membrane actively alleviates oxidative stress by directly scavenging reactive oxygen species and selectively upregulating blood glutathione peroxidase (GSH-PX) activity to remodel endogenous antioxidant defense. This work establishes a clear structure-performance correlation between LA incorporation, porous morphology, gas permeability, and antioxidative capacity, providing an innovative dual-functional design strategy for next-generation ECMO membranes that integrate high efficiency gas exchange with active oxidative stress modulation for high risk metabolically complicated patients.