<p>Saudi Arabia’s Vision 2030 treats financial development as central to economic diversification and environmental reform, yet whether financial development reduces environmental degradation in an oil-dependent economy remains unresolved. This study examines the nonlinear, regime-dependent effects of financial development on production-based CO₂ emissions per capita and the consumption-based ecological footprint using annual data from 1975 to 2024. Methodologically, it combines structural-break cointegration tests with a two-state Markov-switching equilibrium correction model to identify state-specific long-run relationships and short-run adjustments. The findings indicate two highly persistent regimes, with transition probabilities above 0.90. Financial development significantly lowers CO₂ emissions per capita only in the low-emission regime, where the estimated elasticity is -0.034, but has no significant effect in the high-emission regime. By contrast, financial development increases the ecological footprint in both regimes, with elasticities between 0.144 and 0.160. These findings indicate that financial development in Saudi Arabia is not intrinsically environmentally sustainable but operates as a regime-dependent and metric-sensitive mechanism, delivering limited mitigation gains for production-based CO₂ emissions while intensifying broader ecological pressure measured by the ecological footprint. Overall, the results show that financial development in Saudi Arabia supports environmental sustainability only under favorable regimes. This implies that green credit allocation, climate-related disclosure, and prudential regulation are needed to direct financial deepening toward low-carbon and resource-efficient investment under Vision 2030.</p>