The construction industry faces a dual imperative: continued growth to meet the demands of a rapidly expanding global population, and deep decarbonisation to align with planetary boundaries and climate commitments embedded in frameworks such as the European Green Deal and the EU Bioeconomy Strategy. This paper examines the potential of bio-based construction materials to bridge these competing demands, reviewing evidence across a broad spectrum of material categories — including fast-growing plant-based materials, bio-based admixtures and polymer composites for concrete, bio-based polyurethanes, nanocellulose and cellulose aerogels, plant-based biocomposites, and mycelium-based composites. The review demonstrates that bio-based materials offer compelling environmental advantages over conventional petrochemical-derived alternatives, including superior carbon sequestration potential, reduced embodied carbon, improved indoor environmental quality, and compatibility with circular economy principles. The strategic urgency of this transition has been rendered concrete by the 2026 Strait of Hormuz crisis, which triggered severe disruptions to global petrochemical supply chains and exposed the structural vulnerability of European construction to fossil-derived material inputs — reframing bio-based alternatives as a supply security imperative alongside an environmental one. However, the transition from demonstrator projects to mainstream specification practice remains constrained by persistent technical, economic, and regulatory barriers, including inconsistencies in life cycle assessment methodologies, the absence of harmonised performance standards, certification gaps, high initial costs, and fragmented supply chains. Crucially, the review identifies that resolving these barriers depends not only on continued material innovation but equally on governance configurations, policy stability, and actor coalitions, with the conditions under which green finance, circular procurement, and regulatory instruments successfully accelerate material adoption varying substantially depending on who orchestrates systemic coordination.