High-performance flexible pressure sensors with high sensitivity are important components of the systems for healthcare monitoring, human–machine interaction, and electronic skin. Herein, a flexible and highly sensitive pressure sensor composed of ferrosoferric oxide (Fe₃O₄)/carbon nanofibers (FeOCN) was fabricated using three-dimensional electrospinning and further heat treatment methods. The obtained pressure sensor demonstrates a wide working range (0–4.9 kPa) and a high sensitivity of 0.545 kPa⁻¹ as well as an ultralow detection limit of 6 Pa. Additionally, the pressure sensor exhibits a rapid response time, good stability, high hydrophobicity, and excellent flexibility. These merits endow the pressure sensor with the ability to precisely detect wrist pulse, phonation, breathing, and finger bending in real-time. Therefore, the FeOCN pressure sensor presents a promising application in real-time healthcare monitoring.