This study aimed to investigate the impact of intrapartum and post-partum complications and newborn care practices on early initiation of breastfeeding (EIBF). Data for the study came from a prospective cohort study in Ethiopia that recruited and followed pregnant and post-partum women from 2019 to 2021. Resident enumerators conducted interviews at enrolment in 2019 and follow-ups at 6 weeks, 6 months and 1 year post-partum. The present analysis is based on data from the baseline survey and 6 weeks follow-up. Multivariable logistic regression was used to estimate the effects of newborn care practices and intrapartum and post- partum complications on EIBF (the proportion of newborns who initiated breastfeeding within the first hour of birth). Overall, 2660 mother-infant pairs were included in this analysis. After adjustment, EIBF was less likely among women who experienced intrapartum haemorrhage (adjusted odds ratio [AOR]: 0.76, 95% confidence interval [CI]: 0.59-0.97), malpresentation (AOR: 0.46, 95% CI: 0.30-0.72) and convulsions (AOR: 0.48, 95% CI: 0.34-0.66) during childbirth. Mother-newborn skin-to-skin contact increased the likelihood of EIBF (AOR: 1.47, 95% CI: 1.11-1.94). Women who experienced post-partum haemorrhage (AOR: 0.63, 95% CI: 0.47-0.84), retained placenta for more than 30 min (AOR: 0.36, 95% CI: 0.24-0.52) and convulsions after delivery (AOR: 0.57, 95% CI: 0.41-0.79) were less likely to initiate breastfeeding early. Also, women who had a caesarean birth (AOR: 0.28, 95% CI: 0.18-0.41), delivered outside of a healthcare facility (AOR: 0.70, 95% CI: 0.50-0.99) or had twin birth (AOR: 0.43, 95% CI: 0.22-0.85) were less likely to initiate breastfeeding early. Skin-to-skin contact should be encouraged whenever possible, and women with obstetric complications should be encouraged and supported to initiate breastfeeding early.