Background Glaucoma is a chronic optic nerve disease, often asymptomatic in an early stage, which is usually associated with elevated intraocular pressure. Good adherence to ocular hypotensive agents is essential to control the intraocular pressure and optic nerve damage. There is limited information on glaucoma drug adherence and associated factors in Ethiopia, particularly in the study area. Objective To determine the level of glaucoma drug adherence and associated factors among adult glaucoma patients attending Felege Hiwot Specialized Hospital, Northwest Ethiopia, 2019. Materials and Methods A hospital-based cross-sectional study was conducted at Felege Hiwot specialized Hospital from March 2019 to May 2019. A systematic random sampling method was used to select 402 study participants. A structured questionnaire was prepared, and adherence was assessed by using self-report questions. The collected data were entered into Epi data version 4.2.2.1 and exported into Statistical Package for Social Science version 23 for analysis. Tables, graphs, frequency, mean, and standard deviation were used for descriptive statistics. Variables with a p-value of <0.2 in the bivariable logistic regression were entered in the multivariable logistic regression, and variables with a p-value of <0.05 under multivariable analysis were taken as statistically significant factors for glaucoma drug adherence. Results Among a total of 390 study participants, 212 (56.2%) were adherent to their topical medication. Early glaucoma (AOR=2.8: 95% CI =1.29–5.91), normal vision (AOR=1.9: 95% CI=1.15–3.09), urban residence (AOR=1.6: 95% CI=1.03–2.51), family support (AOR=1.7: 95% CI=1.06–2.76) and information from pharmacist (AOR=1.8: 95% CI=1.11–2.99) were significantly associated with adherence. Conclusion The level of glaucoma drug adherence was 56.2% among patients attending Felege Hiwot Specialized Hospital. Early glaucoma, normal visual acuity, family support, information on medication from the pharmacist, and urban residence were positively associated with adherence.