Parenting practices are fundamental to children's psychological adjustment. However, the neural processes involved in real-time parent-child interaction have remained understudied. The present study examined whether and how two core parenting dimensions—autonomy support ("secure base") and emotional warmth ("safe haven")—differentially predict interbrain synchrony in father-child and mother-child dyads, and whether such synchrony predicts children's later psychological symptoms. Leveraging a longitudinal, within-family design, 105 families including fathers, mothers, and children participated (child mean age = 6.63 years, 50.5% girls). Parenting practices were self-reported one month prior to the lab visit, and children's psychological symptoms were reported by parents one year later. During the lab visit, each child engaged in structured collaborative tasks separately with their father and mother while parent-child interbrain synchrony was measured with functional near-infrared spectroscopy (fNIRS) hyperscanning. Paternal autonomy support uniquely predicted greater father-child interbrain synchrony, whereas maternal emotional warmth uniquely predicted greater mother-child interbrain synchrony. Notably, only father-child synchrony significantly predicted fewer attention, internalizing, and externalizing problems, further mediating the link between paternal autonomy support and reduced child attention problems. These findings offer novel neural-level evidence that autonomy support and emotional warmth play distinct roles in shaping parent-child neural dynamics. Interbrain synchrony may thus serve as a key mechanism linking specific parenting practices to children's psychological adjustment, particularly underscoring the role of father-child interactions in early attention development.