Background: Preterm infants are vulnerable humans requiring much care and attention. They may be exposed to irregular noise, light, and odor in the neonatal intensive care unit for a period of several weeks or months. This study was carried out to determine the effect of individualized developmental care on physiological parameters, growth, and transition to oral feeding in preterm infants. Methods: The study was a randomized controlled trial. The sample comprised premature infants meeting the inclusion criteria. They were randomly assigned to four groups: the maternal voice group, the breast milk odor (BMO) group, the incubator cover (IC) group, and the control group. Results: No statistically significant difference was found between the groups in terms of weight, height, and head circumference at time of discharge. Mean SO2 values were statistically higher in the IC group than the other groups; however, the heart rate and respiratory rate were not statistically different in a significant sense between the groups. The briefest duration of transition to total oral feeding was seen in the BMO group. Conclusion: Individualized developmental care practices based on the results of these interventions are likely to support the care of preterm infants. Breast milk odor may ease the transition to breastfeeding.