Background: Mothers of crying babies have difficulty adapting to their roles and problems with breastfeeding and attachment. Objective: This study aimed to assess the impact of the baby calming training provided to primiparous mothers on maternal role perception, maternal attachment, and breastfeeding self-efficacy. Methods: The study was conducted in a randomized controlled experimental design between March 2023 and March 2024 in the gynecology and obstetrics services of a public hospital in northeastern Turkey (Clinical Trial Number: NCT05594836). The research was conducted with a total of 84 primiparous mothers, including 41 intervention and 43 control groups, who met the inclusion criteria. The Baby Calming Training was administered face-to-face in the intervention group, utilizing a baby swaddling blanket, a sleep companion emitting white noise, and a training booklet. The control group received routine care. Data were collected through the Mother and Baby Introductory Information Form, Semantic Difference Scale-Me as a Mother, Maternal Attachment Inventory, Breastfeeding Self-Efficacy Scale-Short Form, and Infant Sleep Activity Record. The data were analyzed using descriptive statistics, Pearson's chi-square test, independent samples t-test, Mann-Whitney U test, Wilcoxon test, mixed design ANOVA analysis, Cohen's d, and 95% confidence interval (CI). This study adhered to CONSORT research guidelines. Results: Mothers in the intervention group exhibited higher mean scores on the perception of maternal role (mean ± SD: 70.37 ± 5.92, t: 8.590, 95% confidence interval [CI]: [1.347-2.375], d: 1.865, p < 0.001), maternal attachment (mean ± SD: 100.42 ± 1.52, U: 151.500, 95% CI: [0.732-0.892], d: 0.828, p < 0.001), and breastfeeding self-efficacy (mean ± SD: 64.00 ± 5.98, t: 8.109, 95% CI: [1.248-2.258], d: 1.757, p < 0.001) than the control group. It was determined that the total sleep time of the babies in the intervention group was higher, and the total crying duration was lower (p < 0.001). Conclusion: The study revealed that infant soothing training for primiparous mothers enhanced maternal role perception, maternal attachment, breastfeeding self-efficacy, and extended infants' sleep duration. Furthermore, infants exhibited reduced crying.