Background: Preterm infants may present sensory processing difficulties as well as developmental disorders. However, studies investigating both early spontaneous movements, and later sensory processing and development functioning are limited. Aims: To examine; (1) early spontaneous movements between the ages of 3 and 5 months, (2) the differences of sensory processing between the ages of 24 and 35 months in infants who had normal and aberrant fidgety movements between 3 and 5 months corrected age, and (3) the relationship between sensory processing and both early spontaneous movements and developmental functioning. Study design: A prospective observational study design. Subjects: Eighty-eight preterm infants (median gestational age 32 weeks, range 23-36) were included. Outcome measures: Early spontaneous movements, including fidgety movements, were assessed according to the General Movements Assessment (GMA), which determines the Motor Optimality Score (MOS). Developmental functioning was assessed using the Bayley Scales of Infant and Toddler Development, Third-Edition (Bayley-III) and sensory processing was assessed with Toddler Sensory Profile-2 between the ages of 24 and 35 months. Results: Sixteen preterm infants (18.1%) displayed aberrant fidgety movements. Median MOS was 25. Infants who displayed aberrant fidgety movements had a lower Bayley-III score in cognitive, language, and motor domains (p = 0.001, p = 0.006, p < 0.001, respectively) and showed more atypical movement sensory processing (p = 0.016) and touch sensory processing (p = 0.018). Fidgety movements were related to typical/atypical movement processing (p = 0.004, r = 0.300). Conclusion: In addition to motor assessment, sensory processing assessment in preterm infants might play a crucial role due to sensory processing difficulties from the early-period of life.