Aim This study aimed to evaluate the effects of using the teach-back method among women with limited maternal health literacy (LMHL) on maternal health literacy(MHL), postpartum health behaviours and maternal-infant health outcomes. Methods A randomized controlled study was conducted in the obstetrics department of Anhui Provincial Hospital, China. A total of 258 pregnant women with LMHL were recruited at the point of admission to the hospital for birth and randomly assigned to the control group (n = 130), where women received routine education sessions, and the teach-back group (n = 128), where women received routine education sessions plus a teach-back intervention. The two groups were assessed in terms of MHL before and after the intervention, breastfeeding execution, uptake of 42-day postpartum check-ups, complete uptake of one-time recommended vaccines, and physical health outcomes. Statistical tests were employed for data analysis. Results There was no significant difference between the two groups in terms of MHL and other social, demographic, and medical status at baseline. After the intervention, the teach-back group had a higher level of MHL (p < 0.001), better postpartum health behaviours in terms of exclusive breastfeeding within 24 hours postpartum (x2 = 22.853, p<0.001), exclusive breastfeeding within 42 days postpartum (x2 = 47.735, p<0.001), uptake of 42-day postpartum check-ups (x2 = 9.050, p = 0.003) and vaccination (x2 = 5.586, p = 0.018) and better maternal-infant health outcomes in terms of the incidence of subinvolution of the uterus (x2 = 6.499, p = 0.011), acute mastitis (x2 = 4.884, p = 0.027), postpartum constipation (x2 = 5.986, p = 0.014), overweight (x2 = 4.531, p = 0.033) and diaper dermatitis (x2 = 10.896, p = 0.001). Conclusions This study shows that the teach-back method is effective for enhancing MHL, leading to positive postpartum health behaviours, and improving postpartum maternal-infant health outcomes among women with LMHL. The teach-back method may play an important role in improving postpartum maternal-infant health and could be considered in maternal health education. Trial registration number Our trial has been prospectively registered at ClinicalTrials.gov (Ref. No.: NCT04858945) and the enrollment date was 26/04/2021.