Left ventricular diastolic dysfunction (LVDD) is commonly seen in hypertensive patients, and it is associated with increased morbidity and mortality. Hence, the detection of LVDD with a simple, inexpensive, and easy‐to‐obtain method can contribute to improving patient prognosis. Therefore, we aimed to evaluate whether there was any association between the electrocardiographic P wave peak time (PWPT) and invasively measured left ventricular end‐diastolic pressure (LVEDP) in hypertensive patients who had undergone coronary angiography following preliminary diagnosis of coronary artery disease. A total of 78 patients were included in this cross‐sectional study. The PWPT was defined as the time from the beginning of the P wave to its peak, and it was calculated from the leads DII and VI. In all patients, LVEDP was measured in steady state. The PWPT in lead DII was significantly longer in patients with high LVEDP; however, there was no significant difference between groups in terms of PWPT in the lead VI. In multivariable analysis, PWPT in lead DII was found to be independent predictor of increased LVEDP (OR: 1.257, 95% CI: 1.094‐1.445; P = 0.001). In receiver operating characteristic curve analysis, the optimal cut‐off value of PWPT in the lead DII for prediction of elevated LVEDP was 64.8 ms, with a sensitivity of 68.7% and a specificity of 91.3% (area under curve: 0.882, 95% CI: 0.789‐0.944, P < 0.001). In conclusion, this study result suggested that prolonged PWPT in the lead DII may be an independent predictor of increased LVEDP among hypertensive patients.