This study aimed to investigate the effectiveness of posterior tibial nerve stimulation (PTNS) in reducing pain, improving quality of life, and decreasing disease severity in patients with fibromyalgia. This prospective, single-blind, randomized controlled trial included female patients newly diagnosed with fibromyalgia who had started duloxetine treatment (30 mg/day). The patients in the study group received six sessions of posterior tibial nerve stimulation, twice weekly, 3-4 days apart, in addition to duloxetine; the controls received duloxetine only. The patients were evaluated three times (at baseline, 1st month, and 3rd month). Pain was evaluated using a numeric rating scale, the short-form McGill Pain Questionnaire, and quality of life with a 36-item short-form health survey (SF-36). Patient functional status and disease severity were evaluated using the fibromyalgia impact questionnaire (FIQ). A total of 64 patients met the inclusion criteria: 22 were ultimately included in the study group and 30 in the control group. Statistical improvements in pain and FIQ scores were observed after treatment in both groups. The SF-36 scores indicated improved vitality only in the 1st month in both groups, with no significant changes in the other quality-of-life subscales in either group. There was no statistical difference between the two groups in terms of changes in pain, FIQ, and SF-36 scores compared with baseline at the 1st month and 3rd month. The addition of PTNS to pharmacological treatment did not contribute to the reduction in pain or improvement in quality of life in fibromyalgia either in the 1st or 3rd month. NIH Clinical Trial Registration Number NCT05937711.