Background and Aim: Mature students have unique strengths and weaknesses compared to traditional students, including higher levels of self-directed learning and motivation, paired with more time and resource limitations, making online and hybrid learning very popular. However, the quality of the hybrid learning environment could impact learning outcomes. The research investigates the role of hybrid learning environments in the learning experience and cognitive engagement of Thai mature students using the Web-Based Learning Environment Instrument (WEBLEI) assessment framework for online environments. Materials and Methods: An online survey was conducted among mature students at a Thai university (n = 290). Data was collected using a questionnaire based on the WEBLEI framework. The data analysis used descriptive statistics and Structural Equation Modelling for hypothesis testing. Results: Hybrid learning environment characteristics of access, interaction, response, and results significantly influenced perceived learning. Perceived learning and academic self-efficacy influenced cognitive engagement. Academic self-efficacy fully mediated the relationship between perceived learning and cognitive engagement. Conclusion: The hybrid learning environment and its characteristics have a direct influence on the learning experience of mature students, with interaction having a particularly strong effect. Students respond to interaction, feedback, and critical reflection about their contributions, with course design and structure, convenience, efficiency, and autonomy on participation also playing a role. To influence cognitive engagement, improving the online learning environment to support perceived learning and particularly academic self-efficacy is critical.