This study investigates the relationship between corporate social responsibility (CSR) and tax aggressiveness among publicly listed firms. Using a panel dataset of 200 non-financial companies listed on the Nigeria Stock Exchange from 2015 to 2022, this paper finds a statistically significant negative relationship between CSR engagement and tax aggressiveness. Firms with higher CSR scores tend to exhibit less aggressive tax planning behavior. The findings support the legitimacy theory and suggest that socially responsible firms prioritize ethical and transparent tax practices.