Background: Despite health benefits to both infants and mothers, many are not breastfeeding as recommended by national guidelines. Prior studies examining the effects of housing insecurity and food insecurity on breastfeeding intention and duration have been limited and yielded mixed findings. Methods: To assess the relationship among housing insecurity, food insecurity, and breastfeeding, we conducted a secondary analysis of a cohort of nulliparous U.S.-born pregnant individuals with a singleton gestation of ≥28 weeks who completed web-based surveys on five occasions over their infant's first year of life. Upon enrollment, we screened participants for housing and food insecurity and participation in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). We examined variations in breastfeeding intentions and practice by housing insecurity and food insecurity, controlling for demographic factors, using multivariable logistic regression. Results: Of 411 participants, 67 (16%) reported housing insecurity, and 48 (12%) reported food insecurity. Participants with housing insecurity were less likely to report exclusive breastfeeding at 6 months (17.9% versus 29.1%, p = 0.06) and significantly less likely to report any breastfeeding at 12 months (34.3% versus 56.9%, p = 0.003) compared to those with secure housing. In both bivariate and multivariable models, housing insecurity was significantly associated with cessation of breastfeeding before 12 months. Food insecurity was not significantly associated with breastfeeding duration or exclusivity. Conclusions: Housing insecurity is associated with and may adversely impact infant feeding, highlighting the need for screening and accessible and affordable family housing, with further investment in food assistance programs such as WIC.