: Oxidative stress (OS) is a major contributor to the development of non-communicable diseases (NCDs) diseases such as cardiovascular disease, diabetes, and cancer. The aim of this study was to investigate the effects of a 10-week community-based lifestyle intervention program on oxidative stress biomarkers in the adult German population. : A total of 175 adults (aged 18-75 years) were assigned to the intervention group (n = 103) and the control group (n = 72). The intervention group participated in a 10-week healthy lifestyle community-based program (HLCP-2) that included empowering individuals with scientific based knowledge on the four important pillars of health: nutritional health (high plant-based), physical health (physical activity), mental health (stress management), and social health (community support and social interactions). The control group received no intervention. Biomarkers of oxidative stress-including total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and lipid peroxidation (LPO)-were assessed via fasting blood samples at four timepoints: baseline (T0), post-intervention (T1), 6 months (T2), and 12 months (T3). : Our study shows significant improvements in the oxidative stress biomarkers among German adults, who participated in the healthy lifestyle community program (HLCP-2). Significant within-group improvements were observed in the IG from T0 to T1 across TAC, SOD, GSH, and LPO (all < 0.01), with sustained effects through T2 and T3. CAT showed a significant group-by-time effect, though within-group changes were not consistently significant. By contrast, the CG demonstrated minimal improvement or worsening of biomarker levels over time, including a notable increase in LPO (T0 to T1: < 0.01). Gender-based analysis revealed a significant increase in catalase activity in females ( = 0.009). Multivariate regression indicated that group assignment was the strongest predictor of improved oxidative stress status, independent of age, sex, and cardiometabolic risk. : These findings suggest that the Healthy lifestyle community program-2 (HLCP-2) had a positive impact on improving oxidative stress and may be a promising tool for reducing the risk of chronic diseases and enhancing longevity. Our study highlights the importance of simple lifestyle choices in improving overall health, offering effective strategies to combat global health challenges in the form of NCDs and promoting healthy aging.