This study evaluated 10-year results of implanting one iStent trabecular micro-bypass stent during cataract surgery in eyes with open-angle glaucoma (OAG) or ocular hypertension. This retrospective, non-randomized study examined 10-year outcomes of iStent trabecular micro-bypass stent implantation with cataract surgery by one surgeon in eyes with OAG [including primary OAG (POAG) and pseudoexfoliative glaucoma (PXG)] or ocular hypertension at a multi-specialty German ophthalmology center. Study visits were conducted preoperatively and at 2.5, 3, 5, and 10years postoperatively; examinations included intraocular pressure (IOP), medications, corrected-distance visual acuity (CDVA), and adverse events. A total of 63 eyes of 45 patients with OAG (n = 60 eyes) or ocular hypertension (n = 3 eyes) and data through 10years were analyzed. Mean preoperative IOP was 18.6 ± 4.4mmHg on 1.83 ± 1.03 mean medications. At study visits through 10years postoperative, mean IOP reduced by 12.9-19.0% (p < 0.005 at all points), and mean medication burden reduced by 37.8-51.4% (p ≤ 0.006 at all points). At 10years postoperatively, 77.8% of eyes had IOP ≤ 18mmHg and 47.6% had IOP ≤ 15mmHg (vs. 50.8% and 25.4% preoperatively, respectively; p = 0.016). One-third (33.3%) of eyes were medication-free vs. 3.2% preoperatively (p < 0.001); 17.5% were on 2-5 medications (vs. 55.6% preoperatively, p = 0.005); and 93.7% of eyes were on the same or fewer medications vs. preoperative. Post-phacoemulsification CDVA improvement was maintained; no filtering surgeries were completed over 10-year follow-up. Significant and safe IOP and medication reductions were observed through 10years after iStent implantation with cataract surgery in patients with OAG or ocular hypertension.