Emotion regulation (ER) difficulties in early childhood are considered potential predictors of later psychopathology, particularly in children of mothers with Borderline Personality Disorder (BPD). This multicenter study examined ER in German-speaking children of mothers with BPD (C-BPD), children of mothers with anxiety/ depressive disorders, and children of mentally healthy mothers (N = 318; Mage = 39.41 months, SD = 22.16; range: 6–84 months, 53.5% female). We hypothesized that C-BPD would display more unfavorable (maladaptive) ER strategies than the other groups. ER was assessed via behavioral observations, analyzing latency, frequency, duration, and variability. Contrary to expectations, children across all groups primarily used adaptive ER strategies. No significant associations emerged between maternal psychopathology and children’s ER (MANCOVAs for adaptive ER strategies by maternal diagnostic group: duration, p > .999, η2 = .008; latency, p > .999, η2 = .009; frequency, p > .999, η2 = .006, variability, p = .668, η2 = .003). Exploratory analyses revealed age-specific and developmentally typical differences in ER strategy use. These findings contribute to the literature on ER in C-BPD and highlight the need for longitudinal studies to clarify how and when early ER patterns may influence later psychopathological outcomes.