Patellectomized patients may have less satisfactory clinical outcomes following total knee arthroplasty due to a decreased extensor mechanism efficiency and potential instability. The literature only reports 3 case series of patients who had a previous patellectomy undergoing a Unicondylar Knee Arthroplasty (UKA) with mixed results. A Minimally Invasive fixed-bearing UKA was performed in a patellectomized patient with excellent postoperative knee stability and clinical outcomes after 5 years. MIS UKA may be a viable option for patellectomized patients with isolated medial compartment osteoarthritis and no preoperative extensor deficiency or instability. Level of evidence IV.