This chapter argues that sustainable finance—once a niche ethical movement—has become a central instrument of geopolitics and a new architecture of power. By redirecting capital toward “planetary stability,” it reshapes industrial policy, supply-chain dependencies, diplomatic leverage, and the hierarchy of states. In a decarbonizing world, controlling green capital flows increasingly means controlling development pathways and defining what “prosperity” will mean. The chapter traces how environmental awareness, climate diplomacy, tech acceleration, financial crises, and political polarization converged to make climate risk a core financial risk. Central banks, asset managers, and governments began treating sustainability not as altruism but as competitiveness and systemic stability. Financial tools—green bonds, climate-linked loans, carbon markets, and especially taxonomies—became instruments of influence. A key battleground is standards: the EU’s technocratic taxonomy, America’s market-driven ESG ecosystem, and China’s state-led classification compete to define what counts as “green,” creating a new extraterritorial power akin to currency dominance or SWIFT. ESG ratings, data access, and methodologies produce hierarchies that can disadvantage countries with weaker governance or limited transparency—often the ones most in need of capital. The chapter then maps green industrial rivalry (EU–US–China), the adaptation of fossil powers through sovereign wealth, and the rising importance of climate data and AI as “climate intelligence.” Finally, it shows the Global South caught between vulnerability and leverage (minerals, justice claims), while finance becomes both opportunity and conditionality. Sustainable finance, the chapter concludes, is the century’s decisive battlefield: the contest to finance the future.