This retrospective study investigated the effectiveness and safety of acupuncture as an adjunctive therapy to topical ibuprofen (TIP) for patients with chronic knee pain (CKP) due to osteoarthritis.This retrospective study analyzed medical records of 84 patients with CKP due to osteoarthritis. These patients were divided into a treatment group (n = 42) and a control group (n = 42). The patients in the treatment group were treated with acupuncture plus TIP, while the subjects in the control group received TIP monotherapy. The primary effectiveness endpoint was assessed by Western Ontario and McMaster Universities osteoarthritis index (WOMAC). The secondary effectiveness endpoints were evaluated by the numeric rating scale (NRS), 12-item Short FormHealth Survey (SF-12, mainly including mental component summary [MCS], and physical component summary [PCS]), and adverse events. All patients received an 8-week treatment. All endpoints were measured pre-treatment and posttreatment.The patients who received acupuncture plus TIP showed better effectiveness in both primary endpoint of WOMAC scale (pain, P < .01; function, P < .01; and stiffness, P < .01) and secondary endpoints of NRS (P < .01), and SF-12 (MCS, P < .01; and PCS, P < .01), than patients who received TIP monotherapy. In addition, both groups had similar safety profile.The results of this study showed that the effectiveness of acupuncture plus TIP may be better than TIP monotherapy for patients with CKP due to osteoarthritis.