Introduction. Nonadherence to antiepileptic medication is the extent of a patient’s passive failure to follow the prescribed therapeutic regimen. The prevalence and impact of nonadherence to antiepileptic medication are high globally. The main purpose of this study was to assess nonadherence to antiepileptic medications and its associated factors among epileptic patients at the University of Gondar Referral Hospital, Gondar, Ethiopia, 2019. Methods. An institutional-based cross-sectional study was conducted among 365 epileptic patients at the University of Gondar Referral Hospital, who were selected by a systematic random sampling technique. Data were collected by face to face interviews using a structured pretested questionnaire. Data were entered into EPI Info version 7 and then exported to SPSS version 22 for analysis. The data were described by descriptive statistics. Binary logistic regression analysis was used as a model, and variables with a p value of less than 0.05 were considered as statistically significant with nonadherence to antiepileptic medications. Results. A total of 356 epileptic patients participated in the study yielding a response rate of 97.5%. The overall prevalence of nonadherence to antiepileptic medications among epileptic patients attending at the University of Gondar Referral Hospital was 38.5% (95% CI: 33.1–43.8). Divorced and/or widowed marital status (AOR: 3.38 (95% CI: 1.54, 7.44)), treatment duration of 3–5 years (AOR = 3.58 (95% CI: 1.38, 9.29)), treatment duration of 5 and above years (AOR: 3.49 (95% CI: 1.53, 7.95)), comorbidity (AOR: 2.42 (95% CI: 1.08, 5.43)), side effects of antiepileptic medications (AOR: 3.36 (95% CI: 1.67, 6.74)), absence of health information (AOR: 1.98 (95% CI: 1.11, 3.52)), epilepsy-related stigma (AOR: 2.81 (95% CI: 1.57, 5.02)), and negative attitude towards antiepileptic medications (AOR: 2.46 (95% CI: 1.36, 4.45)) were significantly associated with nonadherence to antiepileptic medications. Conclusions. Prevalence of nonadherence to antiepileptic medications among epileptic patients at the University of Gondar Referral Hospital was found to be high. Hence, giving health information about epilepsy and its management will help to reduce antiepileptic medications’ nonadherence.