In Eastern cultures, teaching is challenging due to students' increasing needs for autonomy and refusal to be controlled in traditional ways. Understanding the relationship between autonomy-supportive practices and students' learning outcome is essential for assisting teachers to create supportive learning environment to satisfy the needs for autonomy and intrinsic motivation. Using self-determination theory, we investigated how an autonomy-supportive environment related to students' need of autonomy, motivation, and achievement in science and mathematics. We considered the association between the autonomy support from school, teacher, and family and the students' achievement in both science and mathematics. A sample of 810 8th grade students, 15 science teachers and 15 mathematics teachers from 15 schools in Myanmar were included. Multilevel structure equation modelling was used to examine the relationships among variables from both individual and school level. Overall findings indicated that students' perceived teacher and parent autonomy support were significantly associated with the students' engagement, anxiety, and academic achievement in both science and mathematics. Teachers' perceived autonomy from school significantly related to students' perceived autonomy support from their teachers. In addition, teachers' perceived autonomy from school indirectly related to students' achievement in science and directly related to students' achievement in mathematics. The finding also showed no synergistic effect between teacher autonomy support and parent autonomy support on students' outcome variables.