Parents are everyday exposed to intense sensory and emotional stimuli. Hence, it is reasonable that the individual trait of Environmental Sensitivity (ES), capturing individual differences in sensitivity and responsivity to stimuli, holds important implications for parenting. Available evidence suggests that a higher sensitivity to stimuli in parents is mainly a risk factor, but studies are limited for the majority to self-report measures of parenting. Across two independent observational studies involving Italian parents, we investigated the role of ES in parenting during the first year of a child life. In Study 1 (N = 41 mothers and infants tracked from 3 to 9 months), a higher ES initially linked to slightly higher parental intrusiveness at 3 months but shifted to less intrusive behaviors by 9 months. No other ES-parenting associations emerged. In Study 2 (N = 55 mothers of children aged 3 months old), findings showed that a higher ES was associated with less attuned parenting behaviors and more parental stress only in the copresence of parental adverse childhood experiences, with a vulnerability effect. In the same sample, a higher ES was associated with more adaptive parental responses to the child, particularly when respiratory sinus arrhythmia, capturing physiological self-regulation, was higher. To conclude, ES was not related to worse parental competences, but rather it made mothers more receptive to environmental (adverse childhood experiences) and inner physiological (respiratory sinus arrhythmia) factors, for better and for worse. We discuss implications for parenting programs and new direction of studies.