Rongjie Lin, Hai Zhang, Zhuhang Dai, Zihong Wei, Sihui Zhong, Chenghao Xiong, Weilang Hu, Yuansong Feng, Yuhao Dong, Yaxiaer Yalikun, Chenjing Shang, Huaping Wu, Yang Yang
ABSTRACT Flexible pressure sensors offer unique advantages for deep‐sea exploration, yet balancing sensitivity, range, and environmental robustness—especially under extreme hydrostatic pressure and temperature gradients that induce signal drift—remains challenging. Here, we report a fully integrated iontronic pressure sensor for ocean exploration. Through co‐design of a gradient‐microstructured ionogel with a linear‐elastic polyurethane spacer, the sensor achieves an unprecedented broad linear sensing range of 0–10 MPa, sensitivity of 98.4 kPa −1 , and exceptional linearity ( R 2 = 0.996). Notably, the sensor retains repeatability and signal stability under hydrostatic loading up to 55 MPa. Field deployments on a remotely operated vehicle and a manned submersible at depths of ∼1353 and ∼2359 m confirmed stable performance in the bathyal zone. An ultra‐low‐power embedded system (quiescent current: 4 µA) integrated with a thermal compensation algorithm enables autonomous data acquisition, suppressed temperature‐induced drift, and correction accuracy exceeding 95%. This integrated iontronic platform addresses unmet needs for next‐generation deep‐sea monitoring and enables reliable in situ oceanographic sensing.