Background: Inadequate nutrition and poor feeding practices of newborn and infants has turn out to be a major public health concern that has negatively affected the lives of many children and as led to the cause of various forms of deficiencies, also the leading cause of death of most children between 1-5years of age. This study determined the effect of peer counselling on exclusive breastfeeding among mothers attending child welfare clinic in two selected general hospitals in Lagos State, Nigeria.Methods: This study adopted a two group pre-test post-test quasi experimental design. Total enumeration was used to select one hundred and seventy-four (174) participants that participated in the study. Data was collected using a self-developed questionnaire while four research questions were tested using descriptive statistics.Results: Findings indicated that the pre-intervention knowledge mean score of participants on the knowledge of exclusive breastfeeding in the control group was 15.43±4.98 (48.2%) and 14.69±5.16 (45.9%) in the experimental group with a mean difference of 0.74. The post-intervention knowledge mean score of participants on the exclusive breastfeeding in the control group was 15.58±4.83 (48.7%) and 28.97±8.31 (90.5%) in the experimental group with a mean difference of 13.39. Conclusions: The present study demonstrated a significant improvement in the exclusive breastfeeding rate among mothers due to peer counselling exposure, and the interventions have been effective in increasing knowledge and practice of breastfeeding among mothers. It was recommended that knowledge of peer counselling will influence knowledge, practice and behaviours on exclusive breastfeeding rate among mothers.