Background: Although current evidence suggests that there are unique benefits of breastfeeding for mothers receiving comprehensive treatment, including counseling and pharmacotherapy, for opioid use disorder (OUD) and their infants, breastfeeding rates in this population are low. Support and counseling about breastfeeding are key predictors of infant feeding behaviors. Thus, identifying knowledge and attitudes regarding breastfeeding of individuals who work in OUD treatment facilities could offer insight into targets for breastfeeding-promotion interventions in such settings. Materials and Methods: Individuals who work at two urban perinatal OUD treatment centers were e-mailed a link to complete a questionnaire electronically. Breastfeeding knowledge, attitudes, and perceptions of those who completed the questionnaire were described using descriptive statistics. Results: Among the 24 survey respondents, most correctly identified the health benefits of breastfeeding for infants with neonatal abstinence syndrome, whereas less than half correctly identified the health benefits of breastfeeding for all infants. Only 16% reported receiving work-related breastfeeding education. The leading perceived breastfeeding challenges for women in treatment for OUD were (1) concern with transfer of medication (e.g., methadone) through breast milk, (2) daily commutes for treatment, and (3) beliefs that formula is better than breastfeeding. Conclusions: Professionals who work in perinatal OUD treatment centers could benefit from education regarding breastfeeding in mothers in treatment for OUD.