The article explores the use of textile and agri-food by-products as raw materials for producing sustainable cosmetics within the framework of the circular economy (CE), focusing on the systemic design (SD) approach. CE aims to reduce environmental impact through reduction, reuse, recycling, and resource recovery strategies, promoting efficient use of raw materials. In this context, SD facilitates the creation of synergies among different industrial sectors, optimizing process efficiency and supporting resilient economic models. In the cosmetic sector, the use of by-products from other production chains, such as natural textile fibers, agriculture, and food, not only helps reduce environmental footprint by improving product life cycles but also provides ingredients with biocompatible properties that meet growing consumer demand for more sustainable products. Through case study analysis, the article highlights how SD can strategically integrate secondary raw materials and reduce production impacts, generate new economic opportunities, and strengthen value chains. These practices address current environmental challenges and contribute to building a more resilient, sustainability-oriented economy, promoting benefits for both the environment and society.