We investigate the effect of green bond issuance on the cost of bank loans using a global sample of 34 countries and staggered difference-in-differences designs. Robust evidence shows that corporate green bond issuers obtain significantly lower loan costs, reduced collateral requirements, and improved credit ratings. Instrumental variable analyses exploiting industry-level issuance thresholds confirm a causal negative effect, particularly when green bonds signal credible commitments (CBI certified and bonds with green use-of-proceeds). Competing mechanism tests reveal that these benefits stem primarily from enhanced ESG performance and governance rather than information efficiency. Cross-sectional analyses demonstrate stronger effects for firms in high-emission industries, smaller entities, and countries with stringent environmental policies. Endogeneity concerns are addressed through propensity score matching, additional fixed effects, and multiple identification strategies. Our findings establish green bonds as strategic tools for reducing financing frictions, offering actionable insights for issuers, lenders, and sustainable finance policymakers.