Background: Hypertension is a leading cause of morbidity and mortality in adult populations due to complications arising from late detection and poor blood pressure control. Health education has been proven to be an effective strategy in prevention and control of hypertension. However, it’s effectiveness among informal sector workers is under-explored. This study assessed the effect of health education on knowledge of hypertension and its prevalence among market traders in Southeast Nigeria. Methods: The study was conducted in Abakaliki, Ebonyi State Southeast Nigeria using a non-randomized experimental study design comprising an intervention arm and a control arm. Systematic random sampling was used to select 376 adult market traders into the study. Baseline data were collected on participants’ knowledge of hypertension using pretested structured interviewer-administered questionnaire and on their blood pressure status. The intervention group received health education on risk factors, complications, treatment, prevention and early detection of hypertension, while the control group did not. A post-study assessment was carried out after six months using the same study instruments. Bi-variate and multivariate analyses were carried out and statistical significance was set at p < 0.05 Results: The proportion of traders in the intervention group with good knowledge of hypertension increased from 20.7% to 80.7% post intervention (p<0.001); the difference in the control group was not statistically significant. Prevalence of hypertension decreased by 9.8% (p<0.001) from the baseline value of 38.8% in the intervention group but increased in the control group. Predictors of hypertension included having good knowledge of hypertension (AOR: 0.4; CI: 0.2-0.9), being ≥40years (AOR: 2.9; CI: 1.3-6.4), and being single or unmarried (AOR: 2.4; CI: 1.1–5.9) Conclusions: Blood pressure education intervention was effective in improving knowledge of hypertension and reducing prevalence of hypertension. This demonstrates the need to regularly educate market traders on the risk factors, complications, treatment, prevention and early detection of high blood pressure.