BACKGROUND: As the population ages, the use of primary total knee arthroplasty (TKA) is on the rise in the octogenarian population. AIMS: The objective of this study was to compare patient-reported outcomes after TKA in octogenarians versus sexagenarians. METHODS: This retrospective case-controlled comparative study with a propensity score matching analysis was conducted by 251 patients who underwent TKA for degenerative osteoarthritis of the knee. After the propensity score matching analysis, 38 octogenarians and 41 sexagenarians were identified. Range of motion (ROM), degree of flexion contracture, Charlson Comorbidity Index score, Knee Society score (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, the 36-Item Short-Form Health Survey (SF-36), postoperative complications, length of stay, and 90-day mortality after TKA were compared. The degree of improvement of each functional parameter was also assessed. RESULTS: There was no significant difference in the degree of improvement in postoperative ROM, flexion contracture, or KSS. There were only significant differences in length of hospital stay and volume of blood transfusion (p < 0.001 and p = 0.004, respectively). The octogenarian patient group showed significantly inferior outcomes for WOMAC and SF-36 score compared to the sexagenarian patient group (p = 0.009 and p = 0.022, respectively). CONCLUSION: Although the functional improvements after TKA were excellent regardless of age, TKA seemed to contribute little to quality of life in octogenarian patients. Therefore, a careful approach to improving satisfaction with subjective outcomes is needed for octogenarian patients who undergo TKA.