Like many oceanic regions in the world, the Southwestern Indian Ocean (SWIO) is facing challenges to sustain economic growth, livelihoods and food security, while preserving essential habitats to safeguarding the marine ecosystems. Reaching the Global Biodiversity Framework targets and implementing the Blue Economy roadmaps developed in the SWIO region require reliable data and science-based strategies to manage the marine space as well as knowledge-based governance schemes at both national and regional levels. Monaco Explorations, as a platform committed to foster knowledge, sustainable management and protection of the ocean, organised a multidisciplinary expedition in 2022, in partnership with Mauritius and Seychelles, to advance the state of knowledge of unique sites in the SWIO and contribute to setting harmonised ocean governance in the region. This paper sets the general framework of the Monaco Explorations-Indian Ocean (ME-IO) Expedition and its grand objectives. It provides an outline of the projects developed during the expedition and summarizes the main results for an integrated understanding of the biophysical processes and ecological features in the Mascarene Basin, its underwater plateaus and the waters surrounding the islands.