Aims <p>This is a phase I trial, assessing the feasibility, safety, and potential efficacy of intradiscal injection of allogeneic bone marrow-derived clonal mesenchymal stromal cells (BM-cMSCs) in patients suffering from discogenic low back pain (DLBP).</p> Methods <p>Five patients underwent single intradiscal injection of 9 × 10⁶ allogeneic BM-cMSCs and were followed at predefined intervals for 24 weeks. Safety outcomes included monitoring adverse events (AEs), serious adverse events (SAEs), and laboratory assessments. Efficacy endpoints were evaluated over 24 weeks and included Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and SF-36 quality-of-life scores. MRI was performed to assess disc height, apparent diffusion coefficient (ADC), and modified Pfirrmann grading.</p> Results <p>No SAE was observed. Transient injection site pain was the most common AE which resolved within 4–8 days after injection. VAS decreased significantly in three patients, with pain relief sustained through 24 weeks. ODI indicated functional improvement in three patients, with two achieving minimal disability. SF-36 quality of life questionnaire outcomes demonstrated improvements in physical functioning and pain domains in three patients. MRI findings showed modest increases in disc height and apparent diffusion coefficient (ADC) improvements in 2 patients.</p> Conclusions <p>Intradiscal injection of allogeneic BM-cMSCs appears to be safe and feasible as a potential therapy for DLBP, with promising efficacy in reducing pain and improving function and quality of life. Further studies with larger cohorts and extended follow-ups are needed to confirm these findings and explore long-term structural benefits.</p> Trial registration <p>IRCT, IRCT20080728001031N30. Registered 21 October 2021, <a href="https://irct.behdasht.gov.ir/trial/58723">https://irct.behdasht.gov.ir/trial/58723</a>.</p>