The increasing prevalence of media multitasking among adolescents is concerning because it may be negatively related to goal-directed behavior. This study investigated the relationship between media multitasking and executive function in 523 early adolescents (aged 11-15; 48% girls). The three central components of executive functions (i.e., working memory, shifting, and inhibition) were measured using self-reports and standardized performance-based tasks (Digit Span, Eriksen Flankers task, Dots--Triangles task). Findings show that adolescents who media multitask more frequently reported having more problems in the three domains of executive function in their everyday lives. Media multitasking was not related to the performance on the Digit Span and Dots-Triangles task. Adolescents who media multitasked more frequently tended to be better in ignoring irrelevant distractions in the Eriksen Flankers task. Overall, results suggest that media multitasking is negatively related to executive function in everyday life.