Nanoemulsions are pivotal carriers which are increasingly adopted as carriers for poorly soluble active molecules. This review provides a critical overview of ‘green’ nanoemulsions, which are systems based on renewable, biodegradable, and non-toxic components and/or using sustainable production techniques. We here focus on the role of food-grade oils (including poly-unsaturated fatty acid-rich sources) and green excipients, with special attention on the interfacial properties of biosurfactants such as proteins, polysaccharides, and small-molecule surfactants. This review provides a critical overview of the formulation principles, interfacial phenomena, and physicochemical stability of green nanoemulsions, with reference to topical and pharmaceutical applications. The performance of nanoemulsions as delivery systems for bioactive lipids, essential oils, vitamins, carotenoids, phenolic compounds, and conventional drugs is examined through representative case studies. Known limitations, including oxidative instability, compositional variability, and difficulties in large scale production, are analyzed along with future opportunities in multifunctional formulations and sustainable processing. Overall, green nanoemulsions emerge as promising next-generation platforms for safe, effective, and environmentally friendly drug delivery.