The safety and effectiveness of combining surgical peripheral iridectomy (SPI) with goniosynechialysis (GSL) and goniotomy (GT) vs trabeculectomy for intraocular pressure (IOP) reduction remains unknown. To investigate the safety and effectiveness at 1 year of SPI + GSL + GT vs trabeculectomy in advanced primary angle-closure glaucoma (PACG) without cataract. This noninferiority randomized clinical trial was conducted at 8 tertiary eye centers in China. A total of 88 Chinese patients (88 eyes) with advanced PACG without cataract were enrolled from January 2022 to July 2023. Data were analyzed from August 2024 to September 2024. Mean (SD) patient age was 60.3 (7.3) years, and 52 patients (59.1%) were female. Forty-three patients were randomized to SPI + GSL + GT and 45 were randomized to trabeculectomy; 86 patients (97.7%) completed the 12-month follow-up. Participants were randomized 1:1 to receive SPI + GSL + GT or trabeculectomy. The primary outcome was IOP at 12 months (noninferior margin: 4 mm Hg). Secondary outcomes included surgical success (IOP: 5-18 mm Hg, ≥20% reduction from baseline, with or without antiglaucoma medications); postoperative complications and interventions, including bleb massage, suture lysis, or releasable sutures; and number of antiglaucomatous medications prescribed. At 12 months, the SPI + GSL + GT group had a mean (SD) IOP of 15.6 (4.0) mm Hg vs 14.9 (4.2) mm Hg in the trabeculectomy group (difference, 0.5 mm Hg; 95% CI, -1.2 to 2.2; P = .55), which was within the 4-mm Hg noninferiority margin. Qualified success rates were 38 of 43 participants (88.4%) for SPI + GSL + GT and 42 of 45 participants (93.3%) for trabeculectomy (difference, -5.0%; 95% CI, -19.6% to 8.5%; P = .48). However, complete success rates were lower in the SPI + GSL + GT group (26 participants [60.5%]) vs the trabeculectomy group (37 participants [82.2%]; difference, -21.8%; 95% CI, -40.2% to -2.4%; P = .03). Postoperative complications were present for 8 participants (18.6%) in the SPI + GSL + GT group vs 9 participants (20.0%) in the trabeculectomy group (difference, -1.4%; 95% CI, -17.9% to 15.1%; P = .71). Postoperative interventions were lower in the SPI + GSL + GT group (3 participants [7.0%] vs 25 participants [55.6%]; difference, 48.6%; 95% CI, 32.2%-65.0%; P < .001). Median (IQR) numbers of medications used decreased from 2 (0-3) to 0 (0-1) in the SPI + GSL + GT group and from 2 (2-3) to 0 (0-0) in the trabeculectomy group (difference, -0.81; 95% CI, -1.36 to -0.26; P = .004). In this randomized clinical trial among patients with advanced PACG without cataract, SPI + GSL + GT demonstrated noninferiority (4-mm Hg margin) to trabeculectomy for IOP at 12 months, with fewer interventions (including bleb massage, suture lysis, or releasable sutures) but no difference in postoperative medication use. This suggests SPI + GSL + GT as a potential alternative to trabeculectomy for similar cases, pending validation in larger sample sizes with smaller noninferiority margins. ClinicalTrials.gov Identifier: NCT05163951.