Space weather poses an important but under-quantified threat to critical infrastructure, the economy, and society. While extreme geomagnetic storms are recognized as potential global catastrophes, their socio-economic impacts remain poorly quantified. Here we present a novel physics-engineering-economic framework that links geophysical drivers of geomagnetic storms to power grid geoelectric fields, transformer vulnerability, and macroeconomic consequences. Using the United States as an example, we estimate daily economic losses from transformer thermal heating of 1.37 billion USD (95 percent confidence interval: 1.16 to 1.58 billion USD) for a 100-year geomagnetic storm, with power outages affecting 4.1 million people and 101,000 businesses. A 250-year event could raise losses to 2.09 billion USD per day (95 percent confidence interval: 1.84 to 2.34 billion USD), disrupting power for more than 6 million people and 155,000 businesses. Crucially, the framework is scalable and transferable, offering a template for assessing space weather risk to critical infrastructure in other countries. This integrative approach provides the first end-to-end quantification of space weather socio-economic impacts, bridging space physics through to policy-relevant metrics. Our results demonstrate that coupled socio-economic modeling of space weather is both feasible and essential, enabling evidence-based decision making in infrastructure protection and global risk management.