Background The adverse cardiovascular effects of benzodiazepines and Z‐drugs (jointly referred as BZDRs) have been of concern. Yet, little is known about the use of BZDRs in relation to mortality risk among older adults with myocardial infarction history (post‐MI). Methods This study is a secondary analysis of the Alpha Omega Cohort study, comprising post‐MI patients aged 40–60 years. Self‐reported information on the use of BZDRs, including types and dose, was collected at baseline. Four categories of mortality were examined, namely all‐cause mortality, cardiovascular (CVD) mortality, cancer mortality, and non‐CVD/non‐cancer mortality. Associations between BZDRs use, by types and doses, and mortality were estimated with Cox regression models, adjusted for demographic and classic cardiovascular risk factors. Results A total of 433 (8.9%) out of 4837 (21.8% females) patients reported BZDRs use at baseline. During a median follow‐up of 12.4 years, 2287 deaths were documented, of which 825 (36.1%) were due to CVD. BZDRs use was related to a statistically significantly higher risk of all‐cause and CVD mortality; adjusted hazard ratios 95% CI were (1.31 1.41, 1.52) and (1.43 1.14, 1.81), respectively. These relationships were dose‐dependent—patients using BZDRs on an as‐needed basis had similar risks compared to the non‐uses, whereas patients with a daily use schedule and increasing doses had higher risks (p‐value for trend: <0.001). Conclusion BZDRs use was independently associated with a higher risk of all‐cause and cardiovascular mortality in older post‐MI patients, and there was evidence for a dose‐dependent relationship. Clinical trial registration NCT00127452 (www.ClinicalTrials.gov). Key points Use of benzodiazepine and Z‐drugs was associated with a higher risk of all‐cause and cardiovascular mortality in post‐myocardial infarction patients independent of classic CVD risk factors. There was a dose‐dependent relationship—patients with a daily use schedule and with higher doses compared to those using benzodiazepine and Z‐drugs (more sporadically) on an as‐needed basis and non‐users. In older patients with a history of CVD events, benzodiazepine and Z‐drugs should be prescribed cautiously.