We sought to determine whether acupotomy, when combined with topical diclofenac diethylamine emulgel, could (a) reduce pain, and (b) improve functional outcomes in patients with knee osteoarthritis, compared with topical diclofenac alone.This assessor-blinded, single-center randomized clinical trial was conducted at Beijing Hospital of Traditional Chinese Medicine, Capital Medical University. Participants aged 40 to 80 with knee osteoarthritis and a pain score of 4 or higher were randomly assigned, via a computer-generated sequence, to an acupotomy intervention group or a control group. Both groups used diclofenac diethylamine emulgel four times daily for 4 weeks, with acupotomy group receiving four acupotomy sessions. Primary outcome was proportion achieving minimal clinically important pain and function improvements. Analyses followed an intention-to-treat approach, with significance at a two-sided P-value < 0.05. Because of the nature of acupotomy, participants and practitioners could not be blinded.Response rates at 4 weeks were 92.55% (93 of 100) in acupotomy group and 61.54% (61 of 99) in control group. Rate differences were 31.01% (95% CI, 19.70% to 42.33%; P < 0.001). Benefit persisted at week 24 (90.32% vs 38.46%; rate difference, 51.86%; 95% CI, 40.20% to 63.52%; P < 0.001). Secondary outcomes showed greater improvement in NRS and WOMAC scores in acupotomy group at all time points (P < 0.001).Acupotomy combined with topical diclofenac effectively reduces pain and improves function in knee osteoarthritis patients. Acupotomy can be considered an adjunctive therapy. This single-center, assessor-blinded trial was limited by the inability to blind participants and practitioners due to the nature of the intervention.