Competitiveness in the hotel sector and its effect on the environment involves integrating environmental issues in hotel management. Current environmental challenges often require firms to cope with contradictory processes. Ambidexterity is a firm’s capability to deal with conflicting demands and could be helpful in increasing a firm’s environmental management system (EMS) adoption. Furthermore, given the complexity of technological advances, environmental requirements demand inter-firm collaboration. The aim of this study is to further an understanding of how hotels can increase EMS adoption by providing a framework of the contributing effect of alliances and ambidexterity. Results from tests using logistic regression and bootstrapping techniques on a sample of 306 Spanish hotels confirm the importance of ambidexterity because of its positive and direct effect on EMS adoption, and because of the mediating effect, which helps transform the benefits of firms’ participation in strategic alliances into their adoption of EMS. This study contributes to the literature on ambidexterity by highlighting the importance for firms to develop this capability. It also contributes to a better understanding of the drivers of EMS adoption, introducing the integrated effect of hotel participation in alliances and ambidexterity. Hotel managers should endeavor to develop ambidexterity capability to facilitate EMS adoption.