The history of the old silk road dates from the second century BCE to the fifteenth century. Its modern manifestation dates from 2013 when China announced the ‘Silk Road Economic Belt’ and the ‘21st Century Maritime Silk Road’. These land and sea routes became known as the Belt and Road Initiative (BRI). Instead of silk, however, the prized ‘commodity’ from China became infrastructure, investment and its associated connectivity, with expected gains in trade flows and resource access. The BRI includes 150 countries and over 30 international organisations, is likely to draw in a total investment of circa $8 trillion in coming decades, may boost global GDP by over $7.1 trillion annually by 2040, and has numerous economic corridors crossing continents with maritime extensions into the Arctic and the Indo-Pacific. It has been touted by some as a major developmental driver of non-Western globalisation but also has been attacked as a strategic form of geopolitical aggression used to promote China’s global leadership and influence. Beyond these simplistic assessments, the reality of the BRI is that it has been through a continuing strategic evolution since its first announcement in 2013. At first it was a generalised framework to ensure China’s access to resources and markets as part of its ‘going out’ into the global economy, designed to soak up excess production and support domestic job creation. It was thereafter modified several times in its policy emphasis. It was linked to China’s model ‘community of common destiny’ as shared development among partner states, and to the goal of creating an Ecological Civilisation (from 2007) that would embed economic, social and environmental sustainability into the BRI, making it compatible with the UN’s Sustainable Development Goals. This was followed from 2015 onwards by an effort to channel green investment and circular economic models onto the BRI, rebranding it as a Green BRI (GBRI). Unfortunately, over the BRI’s first decade to 2023 this transition was problematic, with only 28–34% of China’s BRI energy engagement being in green or hydropower projects, and with China’s ongoing inability to curtail coal usage despite its planned goal of ‘carbon neutrality’ before 2060. There has also been uneven monitoring of the long-term social and ecological outcomes of many BRI projects, leading to some controversial failures for its megaprojects. China has re-emphasised its commitment to green development, and to supporting high-quality development and cooperation. Whether the BRI will promote sustainable development through economic, technological and green paths of progress or fall short of its promise is explored through three scenarios for the future evolution of the BRI. The Positive Path of development scenario is found to be the most desirable even though it may not be the most probable.