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Livestock systems are of significant concern to global food security, providing basic nutrition and livelihood alongside serious environmental problems. The dual functions of livestock are revealed in this review, i.e, they are essential for billions of animal-derived foods for livelihood and nutrition, but they promote climate change and resource degradation. Smallholder systems within the middle- and low-income countries operate to assist the communities, women included, through poverty reduction and stunting elimination but are liable to environmental stress. Industrial systems within high-income countries seek efficiency at the cost of augmenting inequalities and degradation. Animal-derived foods are nutrient-rich and essential for proper growth and development. However, with the rapid increase in population, the rising demand for meat and dairy products raises sustainability concerns, particularly given the significant contribution of the livestock to greenhouse gas emission and resource consumption. But their implementation requires strategic planning and sustained investment. To reconcile livestock uses with environmental needs, an integrated approach is needed, comprising climate-smart subsidies and carbon pricing. Future research has to be focused on livestock systems that are resilient to climate, impartial access to technology, and incorporation of health and disease resistance aspects for reducing the risk of Zoonosis. Livestock will eventually play a central role in food security, and their sustainable future depends upon the unification of traditional knowledge and science and making food policies more reasonable.