Background: Postnatal period is a joyous yet a challenging period for all mothers. After pain is one of the ailments which often goes unrecognized in this period. Aim of the study: this study aimed to evaluate the effect of foursquare breathing exercises on after pains, initiation of breastfeeding and satisfaction with intervention among postpartum mothers. Design: A quasi-experimental research design. Sample: A convenient sample of 112 postpartum mothers. Setting: This study was carried out at the postpartum ward of El- Mansoura New General Hospital, El-Dakahleya Governorate, Egypt. Tools: Data was collected through three tools, basic data structured interview schedule, which included socio-demographic characteristics and reproductive history; Numerical Pain Rating Scale (NPRS), and Satisfaction Likert Scale. Results: This study reported initiation of breastfeeding within half an hour and one hour after delivery by 26.8% & 57.1% respectively of the study group, compared to 10.7% & 30.4% respectively of the control group. Intensity of after pains was also mild 1 & 2 days after intervention among 69.6% & 94.6% respectively of the former group, compared to 30.3% & 53.6% respectively of the latter group. In addition, most of the study group (96.4%) was completely satisfied with the intervention. Conclusion: This study concluded that four-square breathing exercises significantly reduced the intensity of after pains and enhanced early initiation of breastfeeding as well as achieved satisfaction of postpartum mothers with the intervention. Recommendations: Four square breathing exercises should be incorporated into the nursing intervention protocols of post-partum mothers.