Introduction: The covid-19 pandemic restrict face-to-face breastfeeding counseling. The present study aimed to investigate "the effect of telemidwifery counseling on breastfeeding self-efficacy of primiparous mothers during the covid-19 pandemic". Methods: In this randomized controlled trial, 122 primiparous pregnant mothers referring to health centers from January to May 2022 participated. Random allocation was done using balanced blocks method. In addition to the usual counseling during prenatal care, the intervention group received virtual breastfeeding counseling individually on the social media platform during pregnancy. Breastfeeding self-efficacy, mother's perception of breastfeeding adequacy, and mother's breastfeeding status were investigated on the 5th, 15th, and 45th days after child birth. Results: The mean breastfeeding self-efficacy score on the fifth day after childbirth between the two intervention and control groups was not significantly different, but the mean difference of this score (95% confidence interval) between the two groups on the 15th day equals 4.13 (1.41- 6.86) and on the 45th day it was 6.62 (1.12- 4.41), which was significantly higher in the intervention group than the control group. There was no significant difference in the breastfeeding status of the mothers in the two groups during the follow-up period. The mean score of the mother's perception of breastfeeding adequacy in the intervention group was significantly higher than the control group only on the 45th day after delivery with a mean difference of 1.12(0.53-1.71). Conclusion: Telemidwifery breastfeeding counseling can be suggested as an effective method to increase the breast feeding self-efficacy of primiparous mothers.