Background: The prevalence of hypertension (HTN) is increasing rapidly in Ethiopia, but data are limited on hypertension prevalence in specific workplaces. Therefore, the aim of this study was to assess the prevalence and associated factors of hypertension among federal ministry civil servants. Methods: Institutional based cross sectional study was conducted from February to April 2014. Simple random sampling technique was used to select 655study participants. A standardized questionnaire adapted from The World Health Organization's (WHO) STEP tool was used to collect the data. In this study, HTN was defined as mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) of 140/90 mmHg and above, and patients on regular drug therapy for H. Data were entered into EPI-Info 3.5.2 and analyzed by SPSS version 20. Binary logistic regression model was used to identify associated factors. Odds ratio with 95 % CI was computed to assess the strength of the association and significant level. Result: The prevalence of hypertension was found to be 27.3 % (95 % CI 23.3 - 31 %). Civil servants of age 48 years and above [AOR = 5.88, 95 % CI: 2.36-14.67], age 38-47 years [AOR = 2.80, 95 % CI: 1.18-6.60] and age 28-37 years [AOR = 2.35, 95 % CI: 1.00-5.56]) were more likely to be hypertensive. Similarly, ever cigarette smoking [AOR =2.34(1.31-4.17), family history of hypertension [AOR = 3.26, 95 % CI 1.96-5.40], self-reported Diabetes Mellitus (DM) [AOR = 13.56, 95 % CI: 6.91-26.6], and body mass index (BMI > 25 kg/m2) [AOR = 7.36, 95 % CI: 2.36-14.67] were found to be significantly associated with hypertension. Conclusion: The prevalence of hypertension among federal ministry civil servants was found to be high; which is an indication for institution based hypertension-screening programs especially focusing on those aged 28 years and above, obese, DM patients and cigarette smokers.