We examined how breastfeeding advice in the context of cannabis use differed by race and ethnicity. Data from the 2017-2018 PRAMS (Pregnancy Risk Assessment Monitoring System) survey were used to assess differences in breastfeeding guidance related to cannabis use among 1,213 individuals who self-reported cannabis use 3 months before or during pregnancy. A multivariable logistic regression model was specified to examine the extent to which the odds of receiving prenatal advice against breastfeeding if using cannabis differed by self-reported race and ethnicity. We found that non-Hispanic Black people were four times more likely than non-Hispanic White people to be advised against breastfeeding if using cannabis (adjusted odds ratio 4.1, 95% CI 2.1-8.2). Pregnant non-Hispanic Black people were disproportionately advised not to breastfeed if using cannabis.