Providing quality emergency obstetric care (EmOC) reduces the risk of maternal and newborn mortality and morbidity. There is evidence that over 50% of maternal health programmes that result in improving access to EmOC and reduce maternal mortality have an EmOC training component. The objective was to review the evidence for the effectiveness of training in EmOC. Eleven databases and websites were searched for publications describing EmOC training evaluations between 1997 and 2017. Effectiveness was assessed at four levels: (1) participant reaction, (2) knowledge and skills, (3) change in behaviour and clinical practice and (4) availability of EmOC and health outcomes. Weighted means for change in knowledge and skills obtained, narrative synthesis of results for other levels. One hundred and one studies including before–after studies (n = 44) and randomized controlled trials (RCTs) (n = 15). Level 1 and/or 2 was assessed in 68 studies; Level 3 in 51, Level 4 in 21 studies. Only three studies assessed effectiveness at all four levels. Weighted mean scores pre-training, and change after training were 67.0% and 10.6% for knowledge (7750 participants) and 53.1% and 29.8% for skills (6054 participants; 13 studies). There is strong evidence for improved clinical practice (adherence to protocols, resuscitation technique, communication and team work) and improved neonatal outcomes (reduced trauma after shoulder dystocia, reduced number of babies with hypothermia and hypoxia). Evidence for a reduction in the number of cases of post-partum haemorrhage, case fatality rates, stillbirths and institutional maternal mortality is less strong. Short competency-based training in EmOC results in significant improvements in healthcare provider knowledge/skills and change in clinical practice. There is emerging evidence that this results in improved health outcomes.