To assess the effectiveness and safety of the Preserflo Microshunt (PMS) implantation combined with cataract surgery in open-angle glaucoma (OAG) patients. Retrospective, open-label study conducted on insufficiently controlled OAG patients, who underwent a PMS implant procedure with mitomycin-C 0.2%, either alone or in combination with cataract surgery, and were followed for at least 12 months. Success was defined as an intraocular pressure (IOP) ≤ 18 mmHg and a reduction of at least 20% without (complete) or with (qualified) hypotensive medication. Fifty-eight eyes were included in the study, 35 eyes underwent PMS alone and 23 underwent PMS + Phaco. In the overall study sample, mean IOP was significantly lowered from 21.5 ± 3.3 mmHg at baseline to 14.6 ± 3.5 mmHg at month 12 (p < 0.0001). The IOP was significantly reduced in both groups; p < 0.0001 each, respectively. Ocular hypotensive medication was significantly reduced (p < 0.0001) in both groups. No significant differences were observed in IOP lowering or medication reduction between groups. At month 12, 62.1% eyes were considered as complete success and 82.8% eyes as qualified success. The most common adverse events were device close-to-endothelium, conjunctival fibrosis, and wound leakage. PMS, either alone or in combination with phacoemulsification, may be considered as a valuable option for treating OAG patients.