Goniotomy is an alternative surgery for patients with prior failed surgery for glaucoma. To evaluate the efficacy and safety of goniotomy (GT) in patients with prior failed surgery for glaucoma. A prospective, observational multicentered study was performed for patients who underwent GT with prior single or multiple surgery for glaucoma. Outcome measures included intraocular pressure (IOP) change, best-corrected visual acuity (BCVA) change, ocular hypotensive medication use, and occurrence of adverse events through 12 months. Complete success was defined as a postoperative IOP within 6 to 18mmHg and a 20% reduction from baseline without ocular hypotensive medications. Qualified success was the same as the definition of complete success, except for post-operative use of medication. Logistic regression models were used to investigate the potential factors for surgical success. A total of 38 eyes of 34 patients were included. Twenty-three eyes had only 1 prior surgery, 13 eyes had 2 prior surgeries, 1 eye had 3 prior surgeries, and 1 eye had 4 prior surgeries. At month 12, there was complete success in 42.1% of the eyes and qualified success in 78.9% of the eyes. Preoperatively, the mean IOP was 29.4±6.9mmHg and the median number of glaucoma medications used was 3.0 (2.0, 4.0); this decreased to 16.7±3.6mmHg (43.2% reduction; P<0.001) and 2.0 (0.0, 3.0) (P<0.001) at month 12, respectively. The most common complications included hyphema (13.2%), IOP-spike (7.9%), and corneal edema (5.2%). Older age significantly contributed to surgical success. GT appears to be a safe and effective procedure for patients with prior failed surgery for glaucoma.