Background Controlling blood pressure (BP) leads to significant reduction in cardiovascular risks and associated deaths. In Ethiopia, data is scarce about the level and determinants of optimal BP control among hypertensive patients. This study aimed to assess the prevalence and associated factors of optimal BP control among hypertensive patients attending at a district hospital. Methods A hospital-based, cross-sectional study was conducted among 392 hypertensive patients who were on treatment and follow-up at a district hospital. A structured questionnaire adopted from WHO approach was prepared to collect the data. Medication adherence was measured by the four-item Morisky Green Levine Scale, with a score 3 defined as “good adherence”. Blood pressure was measured, and optimal BP control was 0DEFined as systolic BP < 140 mmHg and diastolic BP<90 mmHg. Both binary and multivariable logistic regressions models were fitted to identify correlates of optimal BP control. All statistical tests were two-sided and a p values <0.05 was considered for statistical significance. Results The mean age of the participants was 58 years (SD±13 years). Over half (53.8%) were females. Three quarters (77.3%) of the participants were adherent to their medications. The overall proportion of participants with optimally controlled BP was 42.9%.Female sex (Adjusted Odd Ratio(AOR) = 1.94, 95% CI: 1.15, 3.26), age older than 60 years (AOR = 2.95, 95% CI: 1.18, 7.40), consumption of vegetables on most days of the week (AOR = 2.16, 95% CI: 1.25, 3.73), physical activity (AOR = 4.85, 95% CI: 2.39, 9.83), and taking less than three drugs per day (AOR = 3.04, 95% CI: 1.51, 6.14) were positively associated with optimally controlled BP. Poor adherence to medications (AOR = 0.18, 95% CI: 0.09, 0.35), having asthma comorbidity (AOR = 0.33, 95% CI:0.12, 0.88) and use of top added salt on a plate (AOR = 0.20, 95% CI:0.11, 0.36) were negatively associated with optimal BP control. Conclusion A higher proportion of hypertensive patients remain with un-controlled BP. Modifiable risk factors including poor adherence to medications, lack of physical exercise, adding salt into meals, being on multiple medications and comorbidities were significantly and independently associated with poor BP control. Evidence-based, adherence-enhancing and healthy life style interventions should be implemented.