The integration of extremophile-derived bioactives into cosmeceuticals and nutricosmetics offers a novel strategy to enhance skin health through both topical and systemic approaches. Extremophile microorganisms, adapted to extreme conditions, produce unique compounds such as ectoine, extremozymes, carotenoids, exopolysaccharides (EPSs), and mycosporine-like amino acids (MAAs). These molecules exhibit antioxidant, anti-inflammatory, photoprotective, and regenerative properties. This review analyzes the molecular adaptations that enable extremophiles to synthesize these compounds, and explores their cosmetic applications, including enzymatic exfoliation, UV protection, hydration, and anti-pollution effects. This paper examines their nutraceutical potential, highlighting systemic benefits such as improved skin elasticity, reduced photoaging, and modulation of the gut–skin axis via prebiotic EPSs. Industrial strategies for sustainable production, such as microbial fermentation, synthetic biology, and green extraction, are discussed. Examples of commercial ingredients like PlusXanthin™, Antarctic-G, and Desertica. Extremophile-derived ingredients combine biological efficacy with environmental sustainability, positioning them as key assets for next-generation skincare. Future directions include clinical validation, regulatory harmonization, and the development of personalized, microbiome-friendly formulations.