This study investigates the effect of environmental and social (E&S) disclosure and managerial entrenchment on investment efficiency. E&S disclosure increases not only capital accessibility but also external monitoring of entrenched managers’ actions. We develop a theoretical model that demonstrates how these benefits and costs of firms’ voluntary E&S disclosure affect investment efficiency. Using a large sample of U.S.-listed firms over the period 2016–2022, we test the model’s predictions and provide empirical evidence suggesting that E&S disclosure is positively associated with investment efficiency and that this effect is stronger for firms with lower managerial entrenchment or those disclosing more financially material E&S information. Our study contributes to the investment efficiency literature by demonstrating the relevance of an incentive-compatible mechanism reflecting managers’ choice of E&S voluntary disclosure to the efficient capital allocation.