Reflective practice is essential in teacher education, enabling pre-service teachers to engage in meaningful professional development and continuously improve their teaching skills. However, barriers such as time constraints, geographic isolation, and crises like COVID-19 often hinder consistent engagement in reflective practices. This study developed and evaluated an online lesson study platform within a university-based teacher education program to address these challenges and support pre-service teachers' professional growth. Using a mixed-methods approach, the study analyzed reflective engagement among 115 pre-service teachers in the Faculty of Education through reflection reports and surveys. The theoretical framework, based on Darling-Hammond's reflective perspective, focused on student learning processes, teaching effectiveness, classroom atmosphere, personal educational philosophy, and continuous growth through reflective dialogue. Qualitative analysis revealed varying levels of engagement in reflective practices, with significant improvements in reflections on teaching methods and student learning. However, challenges remained in reflecting on students' cognitive processes. Quantitative analysis using the McNemar test confirmed statistically significant increases in reflective practice engagement. These findings suggested that online lesson study platforms can provide accessible and practical opportunities for pre-service teacher professional development, overcoming barriers related to location and logistics and supporting global educational goals, particularly Sustainable Development Goals 4 (Quality Education) and 10 (Reduced Inequalities).