Gambling disorder (GD) is a behavioral addiction, in which dysfunctions in prefrontal activity have been proposed as relevant pathophysiological correlates. The aim of the present study was to preliminarily investigate the feasibility of a noninvasive neuromodulation intervention targeting the prefrontal cortex to treat GD in an open-label setting. We included 8 treatment-seeking patients with GD (7 males; 1 female; mean age: 40.6 ± 11.2). The study consisted of 3 phases: (1) outpatient screening phase, (2) 2-week intensive repetitive transcranial magnetic stimulation (rTMS) treatment phase (twice daily, 5 days/week for 2 weeks); and (3) 3-month maintenance follow-up phase (twice daily, once a week). Each high-frequency (15 Hz) rTMS session was delivered targeting the left dorsolateral prefrontal cortex. GD severity and treatment response were assessed at the baseline and during the follow-up. No relevant side effect was reported. We found a 71.2% Gambling Symptom Assessment Scale mean score reduction after 2 weeks of rTMS treatment; the days spent gambling decreased from 19.63 ± 7.96 to 0.13 ± 0.35 days. Clinical improvements were maintained throughout the study period. The lack of a control group limits the interpretation of these results. In conclusion, these results consolidate the rationale that rTMS interventions deserve further investigation as a potential treatment for GD. These protocols should be tested in larger randomized controlled studies, to determine the real benefits of neuromodulation in the clinical course of patients with GD. Registration Number: ClinicalTrials.gov Identifier NCT03336879.