Background: In many cultures, placing a newborn infant on a lap or in a rocking bed is often used to calm the infant. In addition, rocking beds are used to calm crying infants and ease their transition to sleep in some neonatal intensive care units. Purpose: The study was performed to determine the effect that a rocking bed has on comfort, physiological parameters, and cerebral oxygenation level in preterm infants. Methods: Data were collected from 36 preterm infants with a postnatal age of 32-36+6 weeks between March 2021 and September 2022. For each infant, successive rocking bed treatment and control treatment (open bed) were performed in a crossover design. Results: No differences were detected in the physiological parameters and cerebral oxygenation levels of the infants in the measurements made during the rocking bed treatment (P >.05). There was no difference between the treatments in COMFORTneo scores before the start of rocking and at 15 minutes of the intervention (P >.05). However, 15 minutes and 30 minutes after the intervention, the preterm infants in the rocking bed treatment group had significantly lower COMFORTneo scores compared with the control treatment group (F = 9.701, P =.004; F = 7.680, P =.009). Implication for Practice and Research: The rocking bed seems to be a safe practice for preterm infants as there were no statistically significant differences in the physiological parameters and cerebral oxygenation of the infants between the rocking bed and open bed treatments.