The link between corporate environmental performance and financial performance has garnered significant attention in research literature, with findings remaining inconsistent. While many studies indicate that environmental performance enhances financial performance, others suggest that the relationship is either negative or neutral. Utilizing data from 17 Moroccan companies listed on the Casablanca Stock Exchange (Bourse de Casablanca), we assessed the impact of environmental performance on financial performance. To measure environmental performance, our study uses the year of ISO 14001 certification to capture the impact of corporate environmental management on financial performance. Additionally, to elucidate how different financial performance metrics respond to a firm’s environmental efforts, we employ various financial performance indices that reflect diverse market evaluations. Our study reveals a significant impact of environmental performance on the financial performance of selected Moroccan companies listed on the Casablanca Stock Exchange. Companies that invest in robust environmental management practices, such as obtaining ISO 14001 certification, tend to experience enhanced financial outcomes. This indicates that prioritizing environmental sustainability not only fulfills regulatory and ethical obligations but also boosts profitability and market valuation.