PURPOSE: Cross-sectional studies have shown an association between lower help-seeking intentions and greater depressive symptoms among adolescents. However, no longitudinal study has examined the direction of this association. The current study investigated whether help-seeking intentions and depressive symptoms are reciprocally associated at the within-person (individual) level during early to mid-adolescence. METHODS: Longitudinal data on help-seeking intentions and depressive symptoms in adolescents were obtained from a population-based birth cohort study (Tokyo Teen Cohort; N = 3,171) at four time points (10y, 12y, 14y, and 16y). A random intercept cross-lagged panel model was used to evaluate the within-person prospective associations between help-seeking intentions and depressive symptoms. RESULTS: At the within-person level, significant associations were consistently observed between antecedent greater depressive symptoms and subsequent lower help-seeking intentions across all time points (10y-12y: standardized regression coefficient (β) = -0.12, p < .001; 12y-14y: β = -0.07, p < .05; and 14y-16y: β = -0.09, p < .01). Meanwhile, significant within-person associations were partly observed between antecedent lower help-seeking intentions and subsequent greater depressive symptoms from 10y to 12y (β = -0.07, p < .05) and from 14y to 16y (β = -0.12, p < .001). These prospective associations were almost the same when adjusted for the number of potential confidants as a time-varying confounder. DISCUSSION: Adolescents with worsening depressive symptoms may become increasingly reluctant to seek help over time. Proactive early recognition and intervention with support from parents, teachers, and other individuals may facilitate the management of depression in adolescents.