Although low-income pregnant women have high rates of smoking and low rates of breastfeeding, few studies have examined prospective associations between these risk factors in community samples. Doing so may help improve breast-feeding support programs in this population. We used a secondary analysis of 247 low-income pregnant smokers in Memphis, Tennessee, who were interviewed up to 4 times (twice during pregnancy and twice through 6 months postpartum). Smoking cessation during prepartum and postpartum was defined as a self-report of not smoking for ≥1 week and an expired carbon monoxide level of <10 ppm. Multivariable logistic regression analyses were used to determine whether intent to breastfeed was associated with smoking cessation and whether smoking cessation was associated with actual breastfeeding. Models were adjusted for sociodemographic, pregnancy-related, and smoking-related confounders. Thirty-nine percent of participants intended to breastfeed, and 38% did so. Women who intended to breastfeed were 2 times more likely to quit smoking prepartum (adjusted OR = 1.99, 95% CI [1.06, 3.74]), but not postpartum (adjusted OR = 1.27, 95% CI [0.57, 2.84]). Quitting smoking at baseline and during pregnancy was associated with subsequent breastfeeding (adjusted OR 2.27, 95% CI [1.05, 4.94] and adjusted OR = 2.49, 95% CI [1.21, 5.11]). Low-income women who intended to breastfeed were more likely to quit smoking during pregnancy and those who quit smoking at baseline and prepartum were more likely to breastfeed. Simultaneously supporting breastfeeding and smoking cessation may be very useful to change these important health behaviours among this high-risk population.