A fully integrated SoC for multimodality intracranial neuromonitoring is presented in this paper. Three sensors including a capacitive MEMS pressure sensor, an electrochemical oxygen sensor and a solid-state temperature sensor are integrated together in a single chip with their respective interface circuits. Chopper stabilization and dynamic element matching techniques are applied in sensor interface circuits to reduce circuit noise and offset. On-chip calibration is implemented for each sensor to compensate process variations. Measured sensitivity of the pressure, oxygen, and temperature sensors are 18.6 aF/mmHg, 194 pA/mmHg, and 2 mV/degrees C, respectively. Implemented in 0.18 mu m CMOS, the SoC occupies an area of 1.4 mm x 4 mm and consumes 166 W DC power. A prototype catheter for intracranial pressure (ICP) monitoring has been implemented and the performance has been verified with ex vivo experiment.