Sponges (phylum Porifera) are widely distributed across the oceans and form highly-structured habitats (sponge grounds, gardens and reefs) that play key functional roles and deliver numerous ecosystems goods and services. They serve as habitat and nursery to numerous other species including commercially exploited fish, and bath sponges have been harvested for centuries for commercialization of their spongin skeleton, thus supporting local communities’ livelihoods. They are also recognised as prolific sources of compounds with pharmacological potential, thereby providing additional societal and economic benefits to humankind. However, sponges and their habitats are increasingly threatened by human activities (e.g. fisheries, climate change, deep-sea mining, general pollution) in areas within and beyond national jurisdictions (EEZs, ABNJs). Despite significant advances in recent years, knowledge of their biodiversity, distribution, biology and ecology is still sparse and largely fragmentary. This gap in knowledge integration hampers their inclusion in conservation frameworks, compromising the establishment of ecologically representative, interconnected and resilient networks of protected areas, and consequently the achievement of strategic biodiversity targets and commitments. SponBIODIV will use an interdisciplinary approach to build a common and enhanced knowledge base on the biodiversity, biogeography and connectivity patterns of sponges and sponge habitats across the Atlantic Ocean and Mediterranean Sea. The project is anchored on the establishment of a trans-European and pan-Atlantic network of research organizations that will engage with key stakeholders to co-produce, analyse, synthesise and co-deliver data, knowledge and tools in support of evidence-based policies for management and conservation of marine biodiversity, from coastal areas to open ocean and deep-sea ecosystems. Legacy samples and data available at partner institutions will be complemented with new ones collected through a multi-national survey on several case study areas, selected along both environmental and spatial protection gradients, and further integrated with data available in public repositories. Using the latest biophysical and species distribution modelling techniques and genomic sequencing technologies, hotspots of sponge biodiversity, from genes to ecosystems, will be identified and the most significant ecological and evolutionary drivers of their distribution uncovered. Generated knowledge and tools will allow the design of conservation and monitoring strategies, and support the implementation of agreements and policies that will ensure a better management and protection of marine biodiversity, from national to European scales and beyond, in line with the global agenda for sustainable development and conservation of biodiversity.