["Journal of Research in Science Teaching, EarlyView. ", "\nABSTRACT\nAugmented reality (AR) is increasingly integrated into science education, yet the role of teacher support in fostering students' self‐efficacy within AR‐based inquiry learning remains underexplored. This mixed‐methods study investigated the effects of the AR‐based inquiry learning activities on students' science self‐efficacy in various dimensions, as well as the impact of teacher support and students' attitudes toward the features of the designed AR learning environment on students' science self‐efficacy. The study involved 114 Grade 5 students from four classes of a primary school in Singapore. The results showed that the use of AR significantly improved students' conceptual understanding and science communication self‐efficacy. Teachers' emotional support played a key role in conceptual understanding and practical work self‐efficacy, while instrumental support was particularly influential in everyday application. Both forms of teacher support significantly contributed to science communication self‐efficacy. Additionally, students' attitudes toward the AR features partially mediated the effect of emotional support on conceptual understanding self‐efficacy. These findings provide insights for both researchers and practitioners into the importance of and design consideration for adaptive teacher support in optimizing AR‐based science learning in primary school classrooms.\n"]