This study examined how executive function influences emotion regulation and emotional clarity among adolescents aged 15–19, and whether emotional clarity mediates this relationship. A total of 108 high school and university students completed the Operation Span Task, the ERQ, CERQ, and TMMS. Results indicated that adolescents with high executive function scores(> 1 SD) used adaptive regulation strategies more frequently and expressive suppression less frequently than those with low executive function scores(< 1 SD). Among high school students under the age of 18, higher executive function was associated with greater use of adaptive regulation strategies. In contrast, among university students aged 18 and older, higher executive function predicted greater emotional clarity, increased use of reappraisal, and reduced use of expressive suppression. Moreover, emotional clarity mediated the relationship between executive function and reappraisal in the older group.These findings suggest that cognitive competence, including executive function, serves as a key factor in explaining individual differences in emotion regulation during adolescence.