Background Prescription opioid use and related harms have dramatically increased in many countries. Objective To investigate pharmacists' preparedness and confidence to intervene when concerned about supplying prescription opioids and strategies used when concerned about supplying these opioids. Setting Online survey among a representative sample of Australian community pharmacists. Method Pharmacists completed an online survey about their concerns, comfort and strategies used when supplying prescription opioids. Correlates of comfort to intervene and active intervention strategies were explored using multivariable ordered logistic regression and adjusted odd ratios (aOR) and 95% confidence intervals were reported. Main outcome measures Comfort to intervene when concerned about supplying prescription opioids and pharmacists' discussing these concerns with the patient, and the prescriber. Results Most pharmacists were concerned about supplying prescription opioids to patients in the past week. Being female [adjusted odds ratio (aOR) 0.63; 95% confidence interval (CI) 0.47-0.85] was associated with reduced comfort, while practicing within a large chain pharmacy (aOR 1.52, 95% CI 1.08-2.15) was associated with greater comfort to intervene when concerned about prescription opioid supply. Pharmacists practicing in rural areas were significantly less likely than those in capital cities to discuss concerns with patients (aOR 0.66, 95% CI 0.45-0.97). Post-graduate education about substance use disorders was associated with increased likelihood of discussing concerns with patients (aOR 1.54, 95% CI 1.12-2.13). Pharmacists that indicated greater comfort in intervening when concerned about prescription opioids were more likely to discuss concerns with both patients and prescribers. Females were significantly more likely to discuss concerns with prescribers (aOR 1.67, 95% CI 1.22-2.29), whereas years of practice reduced the odds of discussing concerns with prescribers (aOR 0.98, 95% CI 0.97-0.99). Conclusion Considering specific factors such as gender and years of practice to help target pharmacist training may lead to increased comfort in discussing concerns related to prescription opioids, which in turn may improve communication with prescribers and patients.