This pilot study evaluated the immediate and four-week effects of an unloader knee brace on knee-related symptoms and performance-based function in people with knee osteoarthritis (OA) after anterior cruciate ligament reconstruction (ACLR).Individuals with knee OA, five to 20years post-ACLR, were recruited for two within-subject randomized studies: immediate effects (n=18) and four-week effects (n=11). Patient-reported knee-related symptoms (knee pain, perceived task difficulty, confidence, stability) were assessed during hop for distance and step-down tests, while performance-based function was assessed with hopping distance under three conditions: i) no brace; ii) unadjusted brace (sagittal plane support); and iii) adjusted brace (sagittal plane support with varus/valgus readjustment). Participants in the four-week brace effect study were randomized to wear the unadjusted or adjusted brace for four weeks after baseline (no brace) testing, and repeated tests in their allocated brace at four-week follow-up. Friedman tests evaluated differences between the three brace conditions for each variable for the immediate brace effect study (p<0.05), and Wilcoxon signed-rank tests evaluated differences between no brace and allocated brace for the four-week study (p<0.05).The adjusted and unadjusted unloader braces produced immediate improvements in knee confidence during hop for distance, and knee pain during step-down. Following the four-week brace intervention, the allocated brace improved knee confidence, perceived task difficulty and stability during hop for distance; and knee pain, perceived task difficulty, confidence, and stability during step-down.The unloader knee brace, adjusted or unadjusted, has the potential to improve knee-related symptoms associated with knee OA after ACLR.