ObjectiveThis study aimed to assess knowledge, attitudes and practices related to neonatal jaundice among mothers in Shenzhen, China, and analyse associated factors.DesignA cross-sectional study.SettingThis study was conducted in Shenzhen Hospital, Southern Medical University, a university-affiliated, tertiary level A, public hospital in China. On average, 4000 mothers are discharged from this hospital after childbirth each year, most of whom can access a mobile phone and the internet.ParticipantsParticipants were 403 mothers discharged from the study hospital within 48–72 hours after vaginal delivery or 96–120 hours after caesarean delivery between April and June 2021. Participants were recruited using convenience sampling.Primary outcomeMothers’ knowledge, attitudes and practices related to neonatal jaundice, modelled using binary logistic regression.Secondary outcomesFactors associated with mothers’ knowledge, attitudes and practices related to neonatal jaundice.ResultsThe questionnaire was reliable (Cronbach’s alpha=0.802) and valid (scale-level content validity index=0.958). The valid response rate was 96.4%. Only 46.4% of participating mothers had good knowledge about neonatal jaundice and 41.7% indicated they would seek information about neonatal jaundice. A binary logistic regression analysis showed good knowledge about jaundice was associated with a high education level (ie, master’s degree or above; OR=5.977, 95% CI: 1.994 to 17.916, p=0.001), prior education on neonatal jaundice (OR=3.617, 95% CI: 1.637 to 7.993, p=0.001) and male babies (OR=1.714, 95% CI: 1.122 to 2.617, p=0.013). A positive attitude toward jaundice was associated with being cared for by a ‘yuesao’ (maternity matron specialised in caring for mothers and newborns) (OR=1.969, 95% CI: 1.264 to 3.066, p=0.003) and good knowledge about jaundice (OR=1.804, 95% CI: 1.194 to 2.726, p=0.005). Finally, good practices related to neonatal jaundice were associated with prior education on neonatal jaundice (OR=2.260, 95% CI: 1.105 to 4.625, p=0.026) and good knowledge about jaundice (OR=3.112, 95% CI: 2.040 to 4.749, p<0.001).ConclusionMany mothers have poor knowledge about jaundice, especially regarding causes, danger signs and breast milk jaundice. Maternal information-seeking behaviour about neonatal jaundice needs to be improved. Medical staff should incorporate information about the causes/danger signs of jaundice and breast milk jaundice in maternal health education. It is also necessary to strengthen health education for mothers, especially those with low education and no yuesao, and provide reliable websites where mothers can obtain information about neonatal jaundice.