Background: Benzodiazepine long-term use (BLTU) is a public health challenge. We lack data on the consequences of LBTU on the trajectory of treatment-resistant depression (TRD). Objective: To determine the prevalence of BLTU in a nationwide non-selected population of patients with TRD, to determine the rate of patients succeeding at withdrawing benzodiazepines at one year and to determine if persistent BLTU is associated with poorer mental health outcomes. Method: The FACE-TRD cohort is a national cohort of TRD patients recruited in 13 resistant depression expert centers between 2014 and 2021 and followed-up at one year. A standardized one-day long comprehensive battery was carried out, including trained-clinician and patient-reported outcomes, and patients were reevaluated at one year. Results: At baseline, 45.2% of the patients were classified in the BLTU group. In multivariate analysis, compared to patients without BLTU, patients with BLTU were more frequently classified in the "low physical activity" group (adjusted odds ratio (aOR) = 1.885, p = 0.036), and had higher primary healthcare consumption (B = 0.158, p = 0.031) independently of age, sex and antipsychotic consumption. We found no significant difference for personality traits, suicidal ideation, impulsivity, childhood trauma exposure, earlier age at first major depressive episode, anxiety and sleep disorders (all p > 0.05). Despite recommendations for withdrawal, <5% of BLTU patients withdraw benzodiazepines during the one-year follow-up. Persistent BLTU at one-year was associated with higher depression severity (B = 0.189, p = 0.029), higher clinical global severity (B = 0.210, p = 0.016), higher state-anxiety (B = 0.266, p = 0.003), impaired sleep quality (B = 0.249, p = 0.008), increased peripheral inflammation (B = 0.241, p = 0.027), lower functioning level (B = -0.240, p = 0.006), decreased processing speed (B = -0.195, p = 0.020) and verbal episodic memory (B = -0.178, p = 0.048), higher absenteeism and productivity loss (B = 0.595, p = 0.016) and lower subjective global health status (B = -0.198, p = 0.028). Conclusion: Benzodiazepines are over-prescribed in TRD (in almost a half of the patients). Despite recommendations for withdrawal and psychiatric follow-up, <5% of patients successfully stopped taking benzodiazepines at one-year. Maintaining BLTU may contribute to the worsening of clinical and cognitive symptoms and of daily functioning in TRD patients. Progressive and planed withdrawal of benzodiazepines seems therefore strongly recommended in TRD patients with BLTU. Pharmacological and non-pharmacological alternatives should be promoted when possible.< Réduire