This study examines the relation between student experiences of participation in a whole school approach (WSA) and students' self-perceived action competence. We surveyed 902 students in three Norwegian upper-secondary schools participating in an education for sustainable development (ESD) programme. The questionnaire measured students' experiences in decision-making and influencing within a WSA, containing the components: (1) school and leadership, (2) teaching and learning, (3) community connections and (4) student council. We measured students' self-perceived action competence through: (1) knowledge of action possibilities, (2) confidence in one's own influence and (3) willingness to act. A structural equation model indicates a positive relation between student participation in ESD teaching and learning and students' knowledge of action possibilities and confidence in their own influence. Participation through the student council positively related to all action competence components. We found no significant relation between participation in school and leadership or community connections on any action competence factors. It is important to note that this cross-sectional study with a limited number of schools does not establish causality, necessitating further research. Nevertheless, the results suggest that promoting student participation in teaching and learning and facilitating a well-functioning student council can promote students' development of action competence for sustainability.