Background: Increasing breastfeeding rates around the world is one of the most important goals of the World Health Organization. This study was conducted to investigate the impact of smart phone-based education and regular delivery of designed messages on breastfeeding self-efficacy in primiparous mothers. Methods: This study was an educational intervention in which 120 primiparous breastfeeding mothers were randomly allocated into two groups from March 2018 to March 2019. The control group received routine counseling interventions and the intervention group received a smart phone messaging program. We collected the data using demographic questionnaire and Dennis short form breast feeding questionnaire. Self-efficacy levels were compared in the two groups before and after the study procedures. We analyzed the data utilizing Student t-test, chi square, and one way – ANOVA. Results: In this study, 60 mothers were studied in each group, and then the collected data were analyzed. The mean posttest scores in the intervention group (60.40±4.92) and the control group (50.10±7.60) were compared. The results indicated a statistically significant difference between the groups (P<0.001). Working mothers and mothers with a higher level of education had significantly higher self-efficacy score following the intervention (P=0.04 and P=0.05, respectively). Conclusion: Breastfeeding counseling through text, audio, and video messages may increase maternal self-efficacy, particularly in high educated mothers and working ones.