Purpose This study aims to report on outcomes of gonioscopy-assisted transluminal trabeculotomy (GATT) in eyes with primary angle-closure glaucoma (PACG). Methods This study is a prospective, interventional, non-comparative case series. A total of 103 eyes from 88 patients with PACG underwent an ab interno trabeculotomy, using either a 5.0 polypropylene suture or an illuminated microcatheter, with up to 24 months of follow-up. The main outcome measures were intraocular pressure (IOP), number of antiglaucoma medications, success rate (IOP reduction ≥ 20% from baseline or IOP between 6 and 21 mmHg, without further glaucoma surgery) and complication rate. Results The mean preoperative IOP was 21.4 (SD 7.4) mmHg using 2.5 (SD 1.1) glaucoma medications. These decreased postoperatively to 12.1 (SD 2.4) mmHg and 0.8 (SD 1.2) medications, at 24 months ( P  < 0.05). Success rate was 78% at 24 months of follow-up, and complication rate was 4.8%. Conclusion At 24 months of follow-up, our results for GATT in PACG demonstrate that this procedure effectively lowers IOP in this subtype of glaucoma, with a low complication rate.