Left ventricular hypertrophy (LVH) is considered a cardiac condition with life-threatening complications. Detected LVH is a strong predictor of cardiovascular diseases and death. This condition is normally diagnosed at offices. We aimed to determine the prevalence and associated factors of electrocardiographic-LVH (ECG-LVH) among adults in a Thai rural community. A cross-sectional study was conducted in Na-Yao rural community of Thailand in 2020. A total of 638 individuals aged ≥ 20 years were interviewed using standardized structured questionnaires related to demographic information, risk behaviors, comorbidities and anthropometric measurements. LVH was determined by Sokolov-Lyon and Cornell criteria based on the collected electrocardiograms. The prevalence of ECG-LVH among adults was 6.6%. The factors independently associated with ECG-LVH were being male (AORs 2.04, 95% CI 1.05–3.98), history of diabetes mellitus (AORs 1.01, 95% CI 1.01–1.02), and hypertensive crisis ≥ 180/110 mmHg (AORs 7.24, 95% CI 1.31–39.92). However, resting heart rate was negatively associated with ECG-LVH (p < 0.05). Our data emphasized that LVH was one of the significant health problems among adults in a rural community. This condition could lead to severe complications. Thus, effective detection and public health interventions should be provided at the community level.