Maternal self-efficacy in breastfeeding is one of the potential modifiable factors which is consistently linked with positive breastfeeding outcomes. This study aimed to develop a Malay translation of the original English BSES-SF and to conduct a validity and reliability assessment on both antenatal and postnatal questionnaires among 101 pregnant women in their third trimester and 104 women on their first week postpartum. The Malay translation of the English BSES-SF was conducted by using back-to-back translation processes, followed by validity and reliability evaluation. The validated Malay version of the questionnaire BSES-SF was then administered on the respondents. The questionnaire comprised of socio-demographic, antenatal, and breastfeeding information. Furthermore, data on infant feeding method were collected via telephone call made to the respondents at four weeks postpartum. The Cronbach's Alpha value for antenatal BSES-SF questionnaire was0.94, while the value for postnatal BSES-SF questionnaire was 0.95. The factor analysis identified a one-dimensional structure which able to explain 59.02% of the variance for antenatal questionnaire and 60.43% of the variance for postnatal questionnaire. In addition, high antenatal and postnatal breastfeeding self-efficacy scores were significantly associated with the practice of exclusive breastfeeding at four weeks postpartum. As a conclusion, Both Malay versions of the antenatal and postnatal BSES-SF questionnaires are valid and reliable tools to assess breastfeeding self-efficacy among Malaysian mothers.