<b><i>Introduction:</i></b> Abstinence rates after inpatient treatment for alcohol use disorder (AUD) are modest (1-year rate around 50%). One promising approach is to re-train the automatically activated action tendency to approach alcohol-related stimuli (alcohol-approach bias) in AUD patients, as add-on to regular treatment. As efficacy has been demonstrated in well-controlled randomized controlled trials, the important next step is to add alcohol-approach-bias modification (alcohol-ApBM) to varieties of existing treatments for AUD. Therefore, this prospective, multicenter implementation-RCT examined whether adding alcohol-ApBM to regular treatments (various abstinence-oriented treatments including both individual and group-based interventions) would significantly increase abstinence rates compared to receiving regular treatment only, in a variety of naturalistic settings with different therapeutic approaches. <b><i>Methods:</i></b> A total of 1,586 AUD inpatients from 9 German rehabilitation clinics were randomly assigned to receive either ApBM in addition to regular treatment or not. Training satisfaction of patients and therapists was measured after training. Success rates were determined at 3, 6, and 12 months post-treatment. <b><i>Results:</i></b> Return rates of the post-treatment assessments varied greatly between clinics, often being low (18–76%). Nevertheless, ApBM significantly increased success rates after 3 months. After 6 and 12 months, the differences were not significant. ApBM was evaluated mostly positively by patients and therapists. <b><i>Discussion/Conclusion:</i></b> ApBM was an effective add-on to regular treatment of AUD at 3 months follow-up, across a variety of AUD treatment settings. However, low return rates for the clinical outcomes reduced the effect size of ApBM considerably. The application of ApBM proved feasible in varying clinical settings, offering the opportunity to modify automatic processes and to promote abstinence.