Introduction: Medial open wedge high tibial osteotomy (MOWHTO) is one of the modalities to treat unicompartmental knee osteoarthritis (KO). Many studies have shown good outcomes of MOWHTO, but there are no published series of Malaysian patients. The aim of this study is to determine the outcome of MOWHTO in primary medial compartment KO in a university teaching hospital in Malaysia. Materials and methods: This is a retrospective study of patients who underwent MOWHTO in our Joint Reconstruction Unit between 2017 and 2022 with a minimum of 12 months follow-up. Results: Data from a total of 15 knees were reviewed. The mean age of patients was 41.8 years, and the mean BMI was 31.7. The mean Kellgren-Lawrence (KL) osteoarthritis grade was 2.87 (±0.52). The mean hip knee angle (HKA) preoperatively was 12.26° varus and post-operatively was 3.33° valgus. Mean correction of HKA was 13.59°. The results revealed an improvement in all patients, as observed from the significant mean difference between pre-operative (38.53) and post-operative (77.60) Knee Injury and Osteoarthritis Outcome (KOOS) (p-value<0.001) scores. Patients who were above 50 years old showed a significantly better improvement in KOOS score compared to those below 50 (p-value <0.05). There was no significant difference observed between BMI and KOOS score improvement (Fstat=0.580, p-value >0.05). Conclusion: MOWHTO is a good treatment option in medial compartment primary KO with varus deformity among Malaysian population. A larger sample size with a longer follow-up period is needed to draw a definitive conclusion