Background/Objectives: Infertility in both men and women can be significantly influenced by oxidative stress (OS), which occurs due to an imbalance between reactive oxygen species (ROS) and the body’s antioxidant defenses. In women, OS disrupts oocyte maturation, implantation, and the viability of the embryo; in men, it impairs sperm quality, reduces motility, and damages DNA integrity. This review explores existing research on how dietary and lifestyle interventions can reduce OS and enhance reproductive health outcomes. Methods: We conducted a comprehensive review of clinical, translational, and molecular studies exploring the mechanisms by which OS affects fertility, as well as the efficacy of nutritional and behavioral strategies. The interventions evaluated include weight management, regular exercise, micronutrient supplementation, antioxidant-rich diets, smoking and alcohol cessation, and stress-reduction techniques. Results: Specific dietary components such as zinc, selenium, vitamins C and E, and polyphenols have been found to neutralize reactive oxygen species (ROS) and enhance gamete function. OS is additionally reduced through lifestyle modifications, including minimizing harmful exposures, managing stress, and participating in moderate physical activity. Biomarkers such as ROS levels, total antioxidant capacity, 8-OHdG, and DNA fragmentation index are essential for assessing the effectiveness of interventions. Conclusions: Fertility in both sexes can be improved, and oxidative stress significantly reduced, through a multimodal approach incorporating dietary and lifestyle changes. There are encouraging opportunities to improve reproductive health through customized approaches that are informed by biomarker profiles. To incorporate these treatments into regular fertility care, future studies should concentrate on standardized procedures and long-term results.