Smoking during pregnancy and/or not breastfeeding have considerable negative health outcomes for the mother and infant. This descriptive and cross-sectional study determined the relationship between the prediction of smoking cessation success in pregnant women and their breastfeeding attrition prediction during lactation. The other aim of the study was to determine the predictor of smoking cessation success and the factors affecting breastfeeding attrition prediction. The present study was conducted with 131 smoking pregnant women. Data were collected using the Personal Information Form, the Smoking Cessation Success Prediction Scale, and the Breastfeeding Attrition Prediction Tool. A statistically significant and positive correlation was revealed between the Smoking Cessation Success Prediction Scale and the positive breastfeeding attitude (r = 0.349, P < .01). Of the change in positive breastfeeding attitudes, 14.7% was explained by the prediction of smoking cessation success (adjusted R2 = 0.147). The study revealed that the prediction of smoking cessation success increased with an increase in the positive breastfeeding attitude of smoking pregnant women.