A mechanically flexible electrocardiography (ECG) sensor for one-point detection was proposed. The ECG sensor consists of an outer hook-shaped sensing electrode and an inner circular-shaped referencing electrode. The ECG measurement capability was examined by attaching the sensor to the human chest at different positions. Performance of the proposed sensor was then compared with that of the commercial Ag/AgCl electrodes. The results of this letter demonstrated that ECG could be measured using the proposed sensor at only one point on the body.