In order to stimulate the rural bioeconomy and industrial competitiveness, achieve climate mitigation and biodiversity targets, and increase the resilience of production systems, the European Union needs forerunners, both in primary production and industry. Despite the widely recognised and urgent need to substitute fossil raw materials with renewables, under-developed biomass processing methods and business models, and poor understanding of the multiple benefits of well-planned, novel applications currently restrict the implementation of sustainable value chains with balanced environmental, economic and social outcomes. Every step in the novel bio-based fibre value chains targeted by FIBSUN need to be optimised, from cultivation practices, industrial processes, and business models, through to understanding the needs of consumers. The use of novel industrial feedstocks must not lead to undesirable land-use changes, such as the conversion of forest or land currently used for food production into land used for fibre biomass production. Instead, the related land use must be designed to alleviate the harmful effects of desertification, contamination, flooding or mining, by using degraded soils and marginal land to cultivate underutilised biomass feedstocks which can restore soil productivity and enhance the provision of diverse ES. FIBSUN will address these challenges using a multidisciplinary and multi-actor approach involving research organisations, companies and a wide range of stakeholders in a co-creational process aiming at outcomes and long-term impacts promoting green transition in the EU.