Objective: This study's aim to determine the effect of facilitated tucking position applied to late preterm infants on physiological parameters, comfort, and breastfeeding performance. Design: The study was conducted in a randomized controlled experimental design (Clinical Trial number: NCT04704180). Methods: The study was conducted in the neonatal intensive care unit of a state hospital in eastern Turkey between November 2018 and July 2019. The sample consisted of 89 neonates meeting the inclusion criteria. Data were collected using the Neonatal Introductory Information Form, Physiological Parameter Follow-Up Chart, Neonatal Comfort Behavior Scale (NCBS), and Latch Breastfeeding Diagnosis Measurement Form. Facilitated tucking position was applied to the neonates in the experimental group (n = 44) in the early postnatal period. The routine application of the unit was performed on neonates (n = 45) in the control group. Ethical principles were followed at every stage of the study. Findings: It was determined that the physiological parameters (heart rate, oxygen saturation, body temperature, respiratory rate) in the experimental group positioned with facilitated tucking showed a significant improvement compared to the control group (p<0.001). When the mean comfort (Experiment: 9.79±3.63, Control: 15.73±5.13) and LATCH (Experiment: 8.00±1.76, Control: 5.82±2.18) scores of neonates in the experimental group were compared with the control group, a significant difference was found in favor of the experimental group (p<0.001). Implications for practice: It was determined that the physiological parameters, comfort level and sucking success of late preterm infants who were positioned with facilitated tucking in the early postnatal period were positively affected.