The aim of our study was to cross-sectionally compare patient-reported knee function outcomes between people who chose non-surgical treatment for ACL injury and those who chose ACL reconstruction. We extracted Knee Injury and Osteoarthritis Outcome Score (KOOS) and EuroQoL-5D data entered into the Swedish National ACL Registry by patients with a non-surgically treated ACL injury within 180 days of injury (n = 306), 1 (n = 350), 2 (n = 358), and 5 years (n = 114) after injury. These data were compared cross-sectionally to data collected pre-operatively (n = 306) and at 1 (n = 350), 2 (n = 358), and 5 years (n = 114) post-operatively from age- and gender-matched groups of patients with primary ACL reconstruction. At the 1 and 2 year comparisons, patients who chose surgical treatment reported superior quality of life and function in sports (1 year mean difference 12.4 and 13.2 points, respectively; 2 year mean difference 4.5 and 6.9 points, respectively) compared to those who chose non-surgical treatment. Patients who chose ACL reconstruction reported superior outcomes for knee symptoms and function, and in knee-specific and health-related quality of life, compared to patients who chose non-surgical treatment.