ObjectiveTo identify determinants of puerperal sepsis among postpartum women attending East Shoa Zone public hospitals, Central Ethiopia, 2023.Design and settingAn institutional-based, unmatched case–control study was conducted from 19 June 2023 to 4 September 2023, in East Shoa Zone public hospitals.Participants495 postpartum women (100 cases and 395 controls) were selected using systematic sampling techniques. Data were collected through face-to-face interviews and from medical charts using a pretested, structured questionnaire. The AOR with its corresponding 95% CI was used to identify determinant variables. Findings were presented in texts and tables.Outcome measuresThe medical charts of participants were reviewed to identify those who had developed puerperal sepsis.ResultsAnaemia (AOR 6.05; 95% CI 2.57 to 14.26), undernourishment (AOR 4.43; 95% CI 1.96 to 10.01), gestational diabetes mellitus (AOR 3.26; 95% CI 1.22 to 8.74), postpartum haemorrhage (AOR 3.17; 95% CI 1.28 to 7.87), obstructed labour (AOR 2.76; 95% CI 1.17 to 6.52), multiparity (AOR 2.54; 95% CI 1.17 to 5.50), placenta previa (AOR 2.27; 95% CI 1.11 to 4.67) and vaginal examination ≥5 times (AOR 2.19; 95% CI 1.05 to 4.54) were the independent determinants of puerperal sepsis in this study.ConclusionThis study found that gestational diabetes mellitus, anaemia, undernourishment, placenta previa, obstructed labour, postpartum haemorrhage and five or more per-vaginal examinations during labour were the determinants of puerperal sepsis. Therefore, it is recommended that obstetric care providers strictly adhere to guidelines on the number of vaginal exams that should be performed throughout labour and that they perform these exams using the appropriate infection-prevention techniques. In addition, they should provide comprehensive health education on nutrition during pregnancy and postnatal periods and the importance of iron supplements.