Background: High academic anxiety is associated with poor academic performance. One proposed mechanism of this association is that academic anxiety promotes learning avoidance behaviours, which in turn hinders students' opportunities to learn and grow. However, this proposition has not been thoroughly examined, particularly in afterschool learning settings. The present study aimed to address this gap. Aims: First, we investigated whether individual differences in academic anxiety across three domains (mathematics, native language or L1, and second language learning or L2) predicted students' academic avoidance in the corresponding domain in high school. Second, given that individual differences in personality may result in employing different coping strategies to deal with academic anxiety, we examined how mental toughness (MT) moderated the relation between academic anxiety and academic avoidance. Sample: Two waves of longitudinal data that were one semester apart were available for four hundred and forty-four high school students. Methods: Students self-reported their MT, academic anxiety, and academic avoidance (i.e., time spent on studying a subject afterschool) in mathematics, L1, and L2. Results: For students with higher MT, higher mathematics, L1, and L2 anxiety in the first semester predicted more time spent on learning the corresponding subject in the following semester, even after controlling for general anxiety, academic achievement, and initial academic avoidance. Conclusions: These results challenge the proposition that all students with higher domain-specific anxiety are more likely to avoid learning altogether in that domain. Rather, among students from the general school population who generally exhibit low to moderate levels of academic anxiety, higher academic anxiety is associated with more time investment in afterschool learning in mentally tough students.