Women with opioid use disorder (OUD) are less likely to breastfeed compared with the general population, which places their newborns at risk of neonatal withdrawal. Support persons are crucial to successful breastfeeding, yet women with OUD often lack this resource. The purpose of this study was to explore perceptions of support persons of women with OUD influencing breastfeeding decision making. Using an exploratory grounded theory design, in-depth interviews were conducted in August 2018 with women and their identified support persons in eastern North Carolina. Women who breastfed their child in the last 3 years and were in treatment for OUD were recruited from a drug rehabilitation therapy agency, a high-risk obstetric office, and a major medical center. This paper focuses on a subset of 5 women and their support persons. Transcripts were coded in three iterative phases and analyzed to develop a theoretical model titled Breastfeeding Decision Making in an Addiction Trajectory. Memos and field notes informed data analysis. The university’s Institutional Review Board approved this study. Support persons influenced the model through personal behaviors and perceptions of ambiguity, identified in major concepts of the model. Personal behaviors included promotion or hinderance of the recovery–relapse cycle, expression of interest in newborn well-being from breastfeeding through active learning, and providing maternal physical and emotional assistance. Ambiguity was perceived, through health care provider insensitivities, by women and support persons as stigma toward breastfeeding with OUD. Good intentions were either positive, leading to breastfeeding success, or stressful due to perceived ambiguity. Stressful good intentions presented as unsolicited advice and persistent questioning. Support persons were primary resources for women with OUD; although they were ambiguous about breastfeeding, they were supportive of breastfeeding decisions. Perceptions of stigma hinder breastfeeding self-efficacy and jeopardize newborn well-being. Similarly, women’s perceptions of health care provider insensitivity created an aura of stigma. Providers may choose to evaluate personal biases and discuss support-person concerns to break barriers in care, promote maternal breastfeeding self-efficacy, and protect newborn well-being. Future research could include mobile health applications and women in recovery to serve as community health workers.