The purpose of this study is to investigate the effect of project-based learning on students' attitudes toward the environment. In the study that was performed with 39 students who take the "Environmental Education" course, attitude changes toward the environment were investigated in students who developed projects on environmental problems. A mixed-method explanatory design was used to flesh out study results. After being informed about basic environmental concepts and project-based learning, students engaged themselves in group work to develop projects regarding environmental problems. The developed projects were presented with the aim of informing students. According to research results, although a significant gender difference in environmental attitudes was not found, project-based learning had a positive effect on students' environmental attitudes. Students defined project-based learning use in environmental education as an approach that is beneficial, enhancing creativity, encouraging research and providing permanent learning. Students believed this practice helped them define environmental problems more clearly and take on more active tasks in the solution process.