This study aims to determine the effects of kangaroo care at birth on exclusively breastfeeding, infant growth and development according to attachment theory. The study is a randomized controlled trial. The sample of the study consisted of 132 pregnant women between 36 and 38 gestational weeks. Kangaroo care group received 'kangaroo care and breastfeeding training' and practiced kangaroo care at birth. The control group received routine care. Mothers' attachment levels, exclusively breastfeeding duration for six months, growth and development parameters were evaluated for nine months. A statistically significant difference was found between the groups in exclusive breastfeeding duration (KCG: 5.22 mo ± 1.18 mo; CG: 3.47 mo ± 1.51 mo), growth parameters of infants and mothers' attachment scale mean scores for nine months (p < 0.05). There was no significant difference between development parameters of the infants (p > 0.05). It was found that kangaroo care had a positive effect on exclusively breastfeeding and baby's growth.