Background: Overactive bladder (OAB) syndrome affects 10–15% of women, severely impacting their quality of life. First-line treatments include behavioural and physical therapy, and second-line medical treatments include medications such as vaginal oestrogen, anticholinergic medications, and ß3-adrenergic agonists—with potential adverse side effects including dizziness, constipation, and delirium, particularly affecting elderly populations. Third-line treatments include more invasive measures, including intradetrusor botulinum injections or sacral nerve modulation, with percutaneous tibial nerve stimulation (PTNS) being a potential alternative treatment. Aims: The aim of this study was to explore the long-term efficacy of PTNS treatment for OAB in an Australian cohort. Materials and Methods: This is a prospective cohort study. Patients underwent Phase 1 treatment, whereby women received PTNS treatment once per week for 12 weeks. Following Phase 1, women entered Phase 2, whereby they received 12 PTNS treatments over 6 months. Their response to treatment was measured by obtaining data before and after each phase using ICIQ-OAB and the Australian Pelvic Floor Questionnaire (APFQ). Results: Phase 1 included 166 women, with 51 completing Phase 2. There was a statistically significant reduction in urinary urgency (29.8%), nocturia (29.8%), incontinence (31.0%), and frequency (33.8%) compared to the baseline. Patients who completed Phase 2 also showed a statistically significant reduction in urinary frequency (56.5%). Conclusions: Overall, the results from this study are positive and support that PTNS is a minimally invasive, non-surgical, non-hormonal, and effective treatment for OAB. These results suggest that PTNS may be a second-line treatment for patients with OAB not responding to conservative management or for patients aiming to avoid surgical approaches.