Background: Providing early nutritional support through Ying Yang Bao (YYB) can assist children in achieving their full developmental potential. We aimed to examine the lasting impact of YYB and how growth affects neurodevelopment in preschool children. Methods: 1104 children aged 1 year were divided into a YYB control group (YYB-CG) and a YYB intervention group (YYB-IG). Information on basic characteristics, anthropometric measurements, dietary status, YYB consumption, and neurodevelopment for these children was taken annually from 2018 to 2022 until they reached 5 years old. Confounders were well balanced using propensity score matching (PSM), and then 474 pairs of children were included in subsequent analyses. The comparison between groups was performed using t-tests or chi-square analyses. Linear regressions were used to examine the independent associations between children’s dimensions (Z-score for weight relative to age [WAZ], Z-score for height relative to age [HAZ], Z-score for body mass index by age [BAZ], and conditional measures of height- and weight-based growth) and neurodevelopment. Results: Children in the YYB-IG had higher scores in the mental index (MI), the developmental quotient (DQ), height, and BAZ (p < 0.05) and had a lower risk of stunting. Accelerated weight gain from ages 1 to 5 (β (95% confidence interval [CI]): 0.26 (0.08–0.45)) and increased height gain during this period (β (95% CI): 0.68 (0.14–1.23)) were associated with greater MI. A higher WAZ was linked to increased MI at 1 year (β (95% CI): 0.89 (0.09–1.68)), 2 years (β (95% CI): 0.99 (0.20–1.78)), 3 years (β (95% CI): 0.92 (0.15–1.69)), 4 years (β (95% CI): 0.88 (0.09–1.68)), and 5 years of age (β (95% CI): 1.01 (0.28–1.74)). An increased HAZ corresponded with a higher MI score at ages 1 year (β (95% CI): 1.47 (0.75–2.20)), 2 years (β (95% CI): 1.25 (0.49–2.02)), 3 years (β (95% CI): 1.11 (0.31–1.90)), 4 years (β (95% CI): 0.93 (0.12–1.74)), and 5 years old (β (95% CI): 1.17 (0.43–1.90)); higher DQ levels were also recorded at 1 year (β (95% CI): 0.82 (0.10–1.55)) and 5 years of age (β (95% CI): 0.79 (0.06–1.51)). Conclusions: YYB can improve specific areas of neurodevelopment and growth in preschool children. Additionally, children’s linear growth is positively linked to neurodevelopment in those of preschool age.