<p>This study, based on ecosystem theory, constructs an analytical framework using survey data from 11,350 Chinese students in the PISA 2018 sample to systematically analyze the impact of emotional support from parents and teachers on students’ social-emotional competence (SEC). The study examines the mediating role of achievement motivation and the moderating role of self-efficacy. Structural equation modeling results reveal that both parental and teacher emotional support significantly impacts students’ SEC, with parental support having a stronger effect. Specifically, parental emotional support more strongly influences competitive achievement motivation, while teacher emotional support more significantly affects task-oriented achievement motivation. Mediation effect tests show that achievement motivation mediates the relationship between emotional support and students’ SEC, with task-oriented achievement motivation having a greater mediating effect than competitive achievement motivation. Moderation effects suggest that self-efficacy negatively moderates the relationship between competitive achievement motivation and SEC, whereas no significant effect is observed for task-oriented achievement motivation. The findings of this study provide theoretical support for enhancing students’ SEC through emotional support and have practical implications for the cultivation of SEC in adolescents.</p>