Previous cross-sectional and unidirectional longitudinal studies have investigated the associations among perceived parental warmth, positivity, and depressive symptoms among children and adolescents without distinguishing between-person effects from within-person effects. The current study aimed to examine the dynamic longitudinal associations among perceived parental warmth, positivity, and depressive symptoms, including whether positivity functioned as a mediator of the reciprocal relations between perceived maternal/paternal warmth and depressive symptoms at the within-person level encompassing middle childhood to early adolescence. A sample of 3765 Chinese students (45.8% girls; M age = 9.92 years, SD = 0.72; range = 9-12 years at Time 1) completed self-report measures on 4 occasions across 2 years, using 6-month intervals. Random-Intercept Cross-Lagged Panel Models were employed to disentangle between- and within-person effects. (a) Perceived maternal/paternal warmth and depressive symptoms reciprocally and negatively predicted each other; (b) positivity and depressive symptoms reciprocally and negatively predicted each other; (c) perceived maternal/paternal warmth and positivity reciprocally and positively predicted each other; (d) depressive symptoms indirectly predicted perceived maternal/paternal warmth via positivity; (e) perceived maternal warmth displayed earlier and more stable effects on positivity and depressive symptoms than perceived paternal warmth; and (f), no childhood sex differences existed in the observed associations. These findings highlight the longitudinal within-person transactions among perceived parental warmth, positivity, and depressive symptoms, and the differential roles of perceived maternal/paternal warmth. These findings may help provide a potential theoretical framework through which to precisely identify objectives for early intervention.