Autism spectrum disorder (ASD) is reportedly more prevalent in urban areas partly because of better accessibility and affordability to healthcare. With universal health insurance coverage in Taiwan, a previous study has shown no urban–rural disparity in the utilization rate of a child’s preventive healthcare. Under this circumstance, we followed a birth cohort of 176,273 live births from 2006 to 2015 to detect the differences in ASD incidence between urbanicities. After adjusting for socioeconomic factors, children were 1.28 (95% confidence interval (CI): 1.13–1.44) and 1.54 (95% CI: 1.36–1.75) more likely to acquire ASD in satellite and urban areas compared with those in rural areas, respectively. A gradient association between parental educational attainment and ASD incidence was also noted. Greater ASD incidences in more urbanized areas and more advanced educated parents’ children were detected under a circumstance with low barriers to healthcare.