This study examined the impact of curcumin nanomicelles (CNM) supplementation on transitioning ewes and their offspring. Thirty-two crossbred pregnant ewes [Ile-de-France × (Dalagh × Romanov)], confirmed to carry twins, were randomly assigned to a control group (CTRL) or a treatment group receiving 40 mg of CNM per ewe per day. Supplementation began before and continued after delivery. We assessed various parameters, including growth performance, metabolic health, inflammatory markers, hematological profiles, immunoglobulin levels, antioxidant status, and greenhouse gas emissions. CNM supplementation improved growth in both ewes and lambs, consistent with curcumin's known metabolic effects. Significant reductions in inflammatory markers were observed in both ewes and lambs, with decreased neutrophil-to-lymphocyte ratios indicating reduced systemic inflammation. Increased levels of IgG and IgA in both ewes and lambs suggested improved immune competence. Antioxidant biomarkers indicated better management of oxidative stress, with some benefits extended to offspring. CNM had varying effects on methanogen populations and nitrous oxide emissions. It significantly reduced methanogen numbers postpartum, but had no significant effect pre-partum. A slight increase in N2O emissions was observed before delivery, but was not sustained after delivery. These results underscore the complex interactions of metabolic, immunological, and environmental factors influenced by CNM supplementation during the transition period. More research is needed to refine supplementation strategies, evaluate long-term effects, and explore ways to mitigate increased greenhouse gas emissions while preserving health benefits.