Abstract Parenting is known to shape child development, yet the neural processes through which parent–child interaction supports development remain unclear. This longitudinal study tested whether autonomy support and emotional warmth predicted parent–child interbrain synchrony and whether synchrony prospectively predicted children's psychological functioning 1 year later. Using functional near-infrared spectroscopy hyperscanning with 105 families (Mchild age = 6.6 years old), with data collection began in May 2023, interbrain synchrony was computed as wavelet transform coherence across corresponding prefrontal and temporal channels during a dyadic block-building task. Paternal autonomy support predicted greater father–child synchrony (p < .001), and maternal emotional warmth predicted greater mother–child synchrony (p = .015). Father–child synchrony predicted fewer attention, internalizing, and externalizing problems (ps ≤ .01). Findings highlight parent-specific neural pathways linking parenting to child development across time.