IMPORTANCE: Sciatica is commonly caused by herniated lumbar disc and contributes to severe pain and prolonged disability. Although acupuncture is widely used by patients with chronic sciatica, the evidence of its efficacy is scarce. OBJECTIVE: To investigate the efficacy and safety of acupuncture compared with sham acupuncture in patients with chronic sciatica from herniated disk. DESIGN, SETTINGS, AND PARTICIPANTS: This was a multicenter 2-arm randomized clinical trial conducted in 6 tertiary-level hospitals in China of patients with chronic sciatica from herniated disk. Participants were recruited from March 25, 2021, to September 23, 2021, with a final follow-up through September 22, 2022. Data analyses were performed from December 2022 to March 2023. INTERVENTIONS: Participants were randomly assigned to receive 10 sessions of acupuncture (n = 110) or sham acupuncture (n = 110) over 4 weeks. Participants, outcome assessors, and statisticians were blinded. MAIN OUTCOMES AND MEASURES: The 2 coprimary outcomes were changes in visual analog scale (VAS) for leg pain and Oswestry Disability Index (ODI) from baseline to week 4. Secondary outcomes were adverse events. RESULTS: A total of 216 patients (mean [SD] age, 51.3 [15.2] years; 147 females [68.1%] and 69 males [31.9%]) were included in the analyses. The VAS for leg pain decreased 30.8 mm in the acupuncture group and 14.9 mm in the sham acupuncture group at week 4 (mean difference, -16.0; 95% CI, -21.3 to -10.6; P < .001). The ODI decreased 13.0 points in the acupuncture group and 4.9 points in the sham acupuncture group at week 4 (mean difference, -8.1; 95% CI, -11.1 to -5.1; P < .001). For both VAS and ODI, the between-group difference became apparent starting in week 2 (mean difference, -7.8; 95% CI, -13.0 to -2.5; P = .004 and -5.3; 95% CI, -8.4 to -2.3; P = .001, respectively) and persisted through week 52 (mean difference, -10.8; [95% CI, -16.3 to -5.2; P < .001; and -4.8; 95% CI, -7.8 to -1.7; P = .003, respectively). No serious adverse events occurred. CONCLUSIONS AND RELEVANCE: This randomized clinical trial found that in patients with chronic sciatica from herniated disk, acupuncture resulted in less pain and better function compared with sham acupuncture at week 4, and these benefits persisted through week 52. Acupuncture should be considered as a potential treatment option for patients with chronic sciatica from a herniated disk. TRIAL REGISTRATION: Chictr.org Identifier: ChiCTR2100044585.