Drug seizure data indicate the presence of fentanyl in the cocaine supplies nationally and in New York City (NYC). In NYC, 39% of cocaine-only involved overdose deaths in 2017 also involved fentanyl, suggesting that fentanyl in the cocaine supply is associated with overdose deaths. To raise awareness of fentanyl overdose risk among people who use cocaine, the NYC Department of Health and Mental Hygiene pilot tested an awareness campaign in 23 NYC nightlife venues. Although 87% of venue owners/managers were aware of fentanyl, no participating venues had naloxone on premises prior to the intervention. The campaign's rapid dissemination reached people at potential risk of opioid overdose in a short period of time following the identification of fentanyl in the cocaine supply. Public health authorities in states with high rates of opioid-involved overdose death should consider similar campaigns to deliver overdose prevention education in the context of a drug supply containing fentanyl.