Shared decision-making is essential for improving infant prognoses. Medical staff should consider the effect of illness uncertainty and self-efficacy on parents' perceptions of shared decision-making. This study examined the impact of illness uncertainty and self-efficacy on the perception of shared decision-making among parents of infants in the neonatal intensive care unit. A descriptive-analytical cross-sectional study design was used. Data were collected from April to June 2023. A total of 103 parents of infants admitted to the neonatal intensive care unit participated in this study. The participants used a self-report questionnaire that included general characteristics of their infants, uncertainty of illness, self-efficacy and perception of shared decision-making. Data were analysed using descriptive statistics, independent t-test, analysis of variance, Scheffe's test, Pearson's correlation coefficient and multiple linear regression. Illness uncertainty (r = -.659, p < .001, 95% confidence interval = [-1.209, -0.765]) was negatively correlated with self-efficacy, and self-efficacy (r = .255, p = .009, 95% confidence interval = [0.082, 0.569]) was positively correlated with the perception of shared decision-making. Using multiple linear regression, the number of visits to the intensive care unit (β = -1.939, p = .015, 95% confidence interval = [-3.490, -0.389]) and parents' self-efficacy (β = .271, p = .028, 95% confidence interval = [0.030, 0.512]) had a statistically significant effect on the perception of shared decision-making, accounting for 11.9% of the total explanatory power. The results support that higher self-efficacy is associated with a higher degree of perception of shared decision-making among parents of infants in the intensive care unit. Therefore, clinicians might support parents in taking a more active role in shared decision-making by discussing available options with clinicians and reaching treatment plans together. The study suggests creating scales to assess nurses' participation in shared decision-making and recommends educational programmes to boost parents' self-efficacy with infants, significantly affecting perceptions of shared decision-making.