["International Journal of Finance &Economics, EarlyView. ", "\nABSTRACT\nThis paper integrates time‐inconsistent preferences and ESG investment into a dynamic q‐theory framework. We demonstrate that time‐inconsistent preferences induce systematic under‐investment, with the magnitude of inefficiency critically dependent on a firm's reputation. Productivity volatility (σ$$ \\sigma $$) systematically reshapes corporate strategies: rising σ$$ \\sigma $$ reduces investment but increases ESG expenditure. Reputation mediates a strategic trade‐off: low‐reputation firms suffer investment crowding‐out from ESG spending, while high‐reputation firms leverage ESG as a buffer against volatility‐induced distortions. These findings unify the reputation repair hypothesis and buffer effect under a dual‐regime strategy driven by reputation heterogeneity.\n"]