Abstract Background In the last years, functional imaging has given a significant contribution to the clinical decision-making of biochemically relapsed prostate cancer (PCa). Hereby, we present a prospective study aiming to validate the role of [¹⁸F]Fluoro-Methyl Choline ([¹⁸F]FMCH) PET/CT in the selection of PCa patients suitable for stereotactic body radiotherapy (SBRT). Methods Patients with biochemical recurrence limited up to three lesions revealed by [¹⁸F]FMCH PET/CT were enrolled in the present study and treated with SBRT on all active lesions. Systemic therapy-free survival since the [¹⁸F]FMCH PET/CT was considered as the primary endpoint. Results Forty-six patients were evaluated, and a total of 67 lesions were treated. After a median follow-up of 28.9 months, systemic therapy was started in 30 patients (65.2%) and median systemic therapy-free survival was 39.1 months (95% CI 6.5–68.6); 6, 12, and 24-month ratios were 93.5%, 73.9%, and 63.1%, respectively. At univariate Cox regression analysis, Delta PSA demonstrated an impact on systemic therapy-free survival (p < 0.001). Conclusions Based on our findings, [¹⁸F]FMCH PET/CT can identify oligometastatic prostate cancer patients suitable for SBRT, resulting in a systemic therapy-free survival of 39.1 months.