Currently there is a paradox of phosphorus (P) scarcity and overabundance. P is essential for agriculture and food security, but Europe does not have sufficient reserves to meet the growing demand. At the same time, its excessive use has negative environmental impacts, contaminating soils and water bodies. Sustainable P management is therefore of high importance, especially for the SUDOE region, where agroindustry is crucial for its growth and stability. However, such management presents a series of challenges and requires transnational collaboration, involving the multiple actors of the P cycle. ENDORSE proposes a paradigm shift with the implementation of a Circular Economy model, through innovative and local solutions, which combine the symbiosis between the urban and rural sectors. The main objective is to design and implement a transnational strategy for the recovery of P salts from organic waste rich in this nutrient, promoting its subsequent valorization as fertilizers, through more sustainable agricultural practices to guarantee food security and the protection of natural resources in the long term. The novelty of the project lies in i) the cascade precipitation of different P salts, a more robust process with lower operating costs compared to others that precipitate a single salt (such as struvite); ii) the intelligent and sustainable application of the obtained P salts, which will allow for controlled release, maximizing the bioavailability of P and other nutrients, preserving soil health, and minimizing environmental impact. ENDORSE foresees the realization of 4 pilot actions in Castilla y León and Andalusia (ES), in the Northern region (PT), as well as in Occitania and Nouvelle-Aquitaine (FR), from a multi-actor and innovative approach that will function as demonstrative experiences, applicable to other territories. ENDORSE will promote the modernization and attractiveness of the agricultural sector, benefiting especially SMEs, turning the SUDOE area into a smart, innovative, competitive, and sustainable space.