BACKGROUND: Hypnotics are one of the most frequently prescribed drugs worldwide, especially for women, and their chronic use may lead to tolerance, dosage escalation, dependence, withdrawal syndrome, and cognitive impairments, representing a significant public health problem. Consistent evidence from previous studies shows benefits of mindfulness-based interventions (MBIs) for substance use disorders (SUD) and insomnia. However, to date, there is a lack of research about effects of MBIs on reduction/cessation of chronic hypnotic use among women with insomnia. METHOD: The present randomized trial evaluated the efficacy of the 8-week group-delivered mindfulness-based relapse prevention (MBRP) program in an intervention group (IG, n = 34) compared with weekly phone monitoring only in the control group (CG, n = 36) in reducing hypnotic use and insomnia severity over a 6-month follow-up period. RESULTS: There were significant differences between groups at baseline regarding hypnotic use but not insomnia. Group effects on hypnotic use were found immediately after the intervention (bT1 = 2.01, p < 0.001) and at the 2-month follow-up (bT2 = 2.21, p < 0.001), favoring the IG. The IG also had a greater reduction from baseline levels than the control group in insomnia severity at the 4-month (bT3 = 0.21, p = 0.045) and 6-month (bT4 = 0.32, p = 0.002) follow-ups. CONCLUSIONS: The findings provide preliminary evidence of benefits of MBRP for reducing insomnia severity and potentially chronic hypnotic use. However, IG effects on chronic hypnotic use may have resulted from IG and control group differences in chronic hypnotic use at baseline. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02127411.