The conventional understanding of the cerebellum as a sole movement control center has become obsolete, given its role in various higher-order functions, including cognition, emotion, and social processing. As these functions emerge during infancy, it is logical to assume that the cerebellum's functional organization evolve in tandem or preemptively to underpin these functions. However, the longitudinal development of the cerebellum's functional architecture during the crucial early years of infant life remains largely unexplored, highlighting a significant research gap. In this study, leveraging a large cohort of both male and female full-term (FT; n = 155) and preterm (PT; n = 67) infants, we aimed to delineate the development of within-cerebellum and cerebello-cortical functional connections during the first 2 years of life. Our findings highlight comprehensive functional synchronization within the neonatal cerebellum with a striking cortical projection focus on primary sensorimotor and visual cortices. While the within-cerebellum synchronization demonstrated early emergence in neonates and developmental stability during the initial 2 years, the cerebello-cortical projection patterns evolved dramatically, marked by specialization, shifting, and higher-order cortex integration, providing exciting evidence of the cerebellum's potential involvement in higher-order functions from infancy. Furthermore, PT infants exhibited decreased cerebello-cortical connectivity compared with their FT counterparts, suggesting potential developmental alterations. These findings collectively illustrate a dynamic growth pattern of cerebellar functional organization marked by both within-cerebellum stability and cerebello-cortical projection plasticity with significant implications for long-term cognitive and socioemotional development.