Background The reduction in adrenergic activity and anxiety associated with meditation may be beneficial for patients with implantable cardioverter defibrillators. Purpose This study aims to determine the feasibility of a phone-delivered mindfulness intervention in patients with defibrillators and to obtain preliminary indications of efficacy on mindfulness and anxiety. Methods Clinically stable outpatients were randomized to a mindfulness intervention (eight weekly individual phone sessions) or to a scripted follow-up phone call. We used the Hospital Anxiety and Depression Scale and the Five Facets of Mindfulness to measure anxiety and mindfulness, and multivariate linear regression to estimate the intervention effect on pre-post-intervention changes in these variables. Results We enrolled 45 patients (23 mindfulness and 22 control; age, 43–83; 30 % women). Retention was 93 %; attendance was 94 %. Mindfulness (beta = 3.31; p = 0.04) and anxiety (beta = −1.15; p = 0.059) improved in the mindfulness group. Conclusions Mindfulness training can be effectively phone-delivered and may improve mindfulness and anxiety in cardiac defibrillator outpatients.