This study explores the association between early-life vaccine scheduling intensity and autism prevalence across 12 high-income countries, emphasizing implications for neurodevelopment and psychological well-being. Using a cross-national ecological dataset from nations with comparable healthcare systems and diagnostic standards, we examined whether the number and timing of vaccine doses administered to infants under one year correlate with standardized autism incidence rates. Descriptive statistics, partial correlations (controlling for overall vaccination coverage), and multivariate regression models were applied. Countries with higher autism prevalence (USA, Canada, Australia, Japan, South Korea, Singapore) averaged 15 vaccine types and 20 doses for infants ≤1 year, whereas lower-prevalence nations (Norway, Denmark, Finland, Italy, Sweden, UK) averaged 8 vaccines and 9 doses. Strong positive associations emerged between autism prevalence and vaccine types (r = 0.87, p < 0.001) and doses (r = 0.79, p < 0.01). Regression analysis indicated that a 1% increase in vaccine types corresponded to a 0.47% rise in autism prevalence (p = 0.001), explaining 81% of variance. While causality cannot be inferred, these findings highlight patterns warranting further investigation into neurodevelopmental trajectories and psychosocial factors such as parental anxiety and trust in health systems. Gradual scheduling strategies may support optimal cognitive development while sustaining high immunization coverage.