Background Hypertension is a serious threat to public health globally owing to its high prevalence and related complications. It is the main risk factor for cardiovascular disease, kidney disease, eye problems, and death. Self-care practices have been emphasized as a major element in reducing and preventing complications from hypertension. Thus, this study aimed to assess hypertension self-care practices and associated factors in Bale Zone, Southeast Ethiopia. Methods A health facility-based cross-sectional study was conducted at three public hospitals from April 1 to May 31, 2021. Data were entered into Epi-Data version 4.6 and exported to Statistical Package for the Social Sciences (SPSS) version 25.0 for analysis. The study participants were characterized using descriptive statistics. The associations between self-care practice and independent variables were modeled using binary logistic regression analysis. Adjusted odds ratios with a 95% confidence interval were used to estimate the association between self-care practice and independent variables. The statistical significance of the association was declared at p < 0.05. Results This study involved 405 hypertensive patients, with a response rate of 96.7%. The overall level of good self-care practice was 33.1% (95% CI: 28.6, 37.5). The multivariable logistic regression model showed that age under 65 years (AOR = 3.77, 95% CI: 1.60–8.89), good knowledge of hypertension self-care practice (AOR = 6.36, 95% CI: 2.07–19.56), absence of a depression (AOR = 6.08, 95% CI: 1.24–29.73) and good self-efficacy (AOR = 3.33, 95% CI: 1.12–9.87) were independent predictors of good self-care practice. Conclusion The level of good hypertension self-care practice in the study area was low. Hence, it is crucial to expand non-communicable disease control programs and implement public health interventions on self-care for hypertension. Moreover, to enhance hypertension self-care practices, patient-centered interventions are essential.