Psychology is one of the numerous factors that influences students' mathematics achievement, but studies on the influence of psychology on student mathematics achievement are still limited. This study analyzes key factors affecting mathematics achievement through teacher-parent support, stress, and students' well-being in learning mathematics. Data was collected via online questionnaires. Participants of the study are 531 students studying at five secondary schools in Bandung, Indonesia. The data were analyzed using the structural equations modeling approach using SMART-PLS 3.0 software. The results showed that interest in learning was the most significant factor affecting students' mathematics achievement. Moreover, teachers have a more substantial effect than parents' support, which does not significantly reduce the students' stress levels. The academic and emotional support of teachers and parents reduces students' stress levels while increasing their feelings and interest in learning mathematics. This study provides essential results for school teachers and parents to improve students' mathematics achievement at the secondary school level.