Background/Objectives: Art-based interventions have been shown to enhance communication skills in children with autism spectrum disorder (ASD), yet their impact on prefrontal hemodynamics remains unclear. Methods: This study employed functional near-infrared spectroscopy (fNIRS) to examine hemoglobin oxygenation (HbO) changes in the prefrontal cortex of school-age children with ASD, providing empirical support for its therapeutic efficacy. Sixty age-matched children participated in a 9-week art therapy program, including twenty ASD children and forty typically developing peers. Assessments included self-portrait drawing (SPD), the Diagnostic Drawing Series (DDS), and the General Quality of Life Inventory (GQOL-74). In addition, we performed fNIRS measurements in the ASD participants and observed changes in prefrontal HbO at rest and while drawing. Results: The drawing intervention significantly enhanced drawing ability, emotional expression, and cognitive skills, with the intervention group outperforming the controls. ASD participants exhibited distinct prefrontal connectivity patterns with visual, motor, and language-related regions, including the dorsolateral prefrontal cortex, frontal eye field, and Broca’s area. Task-based painting interventions indirectly influenced the frontal lobe’s hemodynamic characteristics, indicating drawing intervention as an effective intervention for ASD.