Urban flooding is a widespread and impactful natural hazard, presenting considerable challenges to urban areas. Integrating peri-urban forests (PUFs) into flood management strategies has emerged as a promising approach to mitigate flood hazards. Citizen engagement in PUF management can enhance flood risk reduction efforts. A notable research gap exists in understanding the factors influencing citizens’ intentions to participate in PUF management for flood mitigation. To address this gap, this study investigates the determinants shaping citizens’ intention to engage in PUF management efforts. Using an extended Theory of Planned Behavior framework—which incorporates environmental awareness and risk perception—this research surveyed visitors to PUFs in Tehran. Structural equation modeling with SmartPLS was applied to examine the relationships among these variables. The findings reveal that attitudes, subjective norms, perceived behavioral control, and environmental awareness significantly influence citizens’ intentions. In contrast, perceived risk had no significant effect. This study highlights the importance of fostering positive attitudes toward PUF management, creating a supportive social environment, empowering individuals with knowledge and resources, and emphasizing environmental awareness in flood hazard reduction. The results provide empirical evidence supporting the inclusion of environmental awareness as a key determinant in an extended behavioral model. Enhancing citizens’ understanding of the immediate benefits of PUFs is crucial for promoting active participation in flood mitigation initiatives.