Maternal affect contributes to children’s psychosocial adjustment. How maternal daily affect intensity and dynamics (i.e., inertia and variability) are associated with adolescents’ psychopathological symptoms, however, remains unclear. This preregistered study examined (1) associations of maternal day-to-day positive and negative affect intensity, inertia, and variability with psychopathological symptoms in adolescence and young adulthood, and (2) how mother–adolescent affect congruency moderates these associations. Mother–adolescent dyads (N = 488) reported positive and negative affect in 75 daily assessments across ages 13 – 17 years. Adolescents rated their psychopathological symptoms at ages 14 – 18, 20, and 27 years. Maternal affect intensity was associated with adolescent psychopathological symptoms, while maternal affect dynamics were inconsistently associated with symptoms in young adulthood. Mother–adolescent affect congruency only moderated the effects of positive affect intensity and variability, in that high-congruent adolescents reported lower internalizing symptoms at age 20 than low-congruent adolescents. No other interaction effects were found. While maternal affect intensity and dynamics seem to contribute to youth psychopathology, evidence for the role of mother–adolescent affect congruency remained limited.