Empirical literature on the trajectory of task performance in children is currently scarce. Therefore, this study investigates both the developmental trajectory of flanker task performance in children and the association with the development of teacher-reported problem behavior. Five waves of flanker performance and behavioral and emotional problems were drawn from a large longitudinal sample of elementary school children in the Netherlands (1424 children, ages 7 to 12 years). Latent growth curve modeling (LGM) identified a piecewise decrease in flanker response time: the steepest decline was found from 7 to 9 years old. Boys had lower levels of response time at age 7 than girls. Children showed a linear decrease in behavioral and emotional problems over time. Parallel LGMs revealed that lower levels of initial flanker response time were associated with a stronger decrease in anxiety problems and oppositional defiant-related behavior. A faster decline in response time was associated with a faster decline in depression problems, attention deficit hyperactivity-, and oppositional defiant-related behavior. Results offer insight into the normative development of performance monitoring in childhood and the link between behavioral measures of performance monitoring and behavioral and emotional problems. Future research should focus on the directionality of the association between performance monitoring and psychopathology.