Overnutrition is a recognized risk factor for hypertension, but evidence is lacking among hypertensive patients for tailored dietary interventions. This study assessed dietary factors in 331 hypertensive patients in southwest Ethiopia. The data was collected through a questionnaire and analyzed using factor analysis. Body mass index (BMI) was calculated, and a BMI above 25 kg m−2 was considered overnutrition. An ordinal logistic regression model was used to model the data and control confounders. Adjusted odds ratio and p-values were reported. Among the 331 respondents, consumption of cereals and grains (57.0%); roots and tubers (58.5); and legumes (50.0%), while 28.6% drink alcohol, was common. About 29.0% (24.1–34.2) had overnutrition (22%, 17.6–26.6%, overweight and 7.0%, 4.5–10.3%, obesity). While the predicted odds of overnutrition were higher among males (AOR = 2.85; 1.35–6.02), married (AOR = 1.47; 0.69–3.12), illiterates (AOR = 2.09; 1.18–3.72), advanced age (AOR = 1.65; 0.61–4.61), government employees (AOR = 6.83; 1.19–39.2), and urban dwellers (AOR = 4.06; 1.76–9.36), infrequent vegetable consumption (AOR = 1.47; 0.72–2.96) and lower and higher terciles of cereals and animal-source food consumption (AOR = 1.56; 0.72–3.34). Overnutrition among hypertensive patients was significantly high and associated with unhealthy dietary consumption, educational status, residence, and occupation, emphasizing the need for targeted dietary counseling.