Abstract Background: Herbal medicines are increasingly used globally and are a more affordable and accessible therapeutic option than conventional medicines. Little is known about their use in breastfeeding mothers and their potential effects on both mother and child. This study aimed to determine the prevalence, socio-demographic determinants, and commonly used herbal medicines among breastfeeding mothers in Lagos state, Nigeria. Methods: A cross-sectional survey of breastfeeding mothers attending primary healthcare centres across Lagos state was conducted. Data were collected using a structured and validated intervieweradministered questionnaire and analysed using descriptive and inferential statistics. The association between socio-demographic characteristics and herbal medicine use was assessed using bivariate analysis. Factors related to herbal medicine use were assessed using logistic regression and the effects were measured with odds ratio along with 95% confidence intervals. p-value <0.05 was considered significant. Results: Of the 400 respondents, 68.3% used herbal medicines for various reasons; however, only 7% reported using them for breastfeeding-related reasons. Herbal medicines were mainly used to treat malaria and typhoid fever (27%). 'Agbo,' a multi-herbal concoction (49%), was the most frequently used herbal medicine. Identified predictors of herbal medicine use included location, tribe, religion, parity, and occupation. Almost 60% of the mothers believed that herbal medicines are more effective than conventional medicines in treating certain illnesses Conclusion: Herbal medicine use is relatively common among breastfeeding mothers in Lagos, Nigeria. Factors related to herbal medicine use included religion, tribe, location, parity, and occupation. Herbal medicines commonly used by this population deserve further research for safety and efficacy for acclaimed use.