Non-Progressive Congenital Myopathy is a disease characterized by muscle weakness, and unfortunately, there is no conventional treatment. In the last decade, regenerative medicine practices have become a rising value, and Mesenchymal Stem Cells (MSCs) have fascinating outcomes in regenerative medicine with their high regenerative capacities, their ability to regulate with paracrine secretions, and their immunological properties. Based on our experience in our previous clinical studies, Wharton's-Jelly-derived (WJ-)MSCs are the most suitable source for muscle diseases among all MSC sources. In this study, we evaluated the outcomes of 10 doses of WJ-MSC transplantation to the patient diagnosed with Non-Progressive Congenital Myopathy. A 17-year-old female with a SPEN-1 mutation, Non-Progressive Congenital Myopathy patient received 10 times as 1×10⁶/kg in the intra-arterial, intramuscular and intravenous administration of allogenic WJ-MSC. Before and after the treatment, the patient was followed-up with the upper extremity scale, Vignos lower extremity scale, muscle strength scale, functional independence measure, and evaluation of Serum creatine kinase (CK) levels. Improvement in both upper extremity scale and Vignos lower extremity scales, increasing in muscle strength, and decreasing in CK-level were detected. Although transplantation of WJ-MSC cannot treat any genetic-based diseases, they may benefit in alleviating clinical outcomes of disease. More importantly, WJ-MSC transplantation may offer a better quality of life by alleviating the symptoms of this rare disease with no treatment option that can be provided in conventional methods.