This paper focuses on CMOS biosensor technologies for cellular biosensing applications. We first present our technologies to achieve on-CMOS cell culture, maintenance, and differentiation, as the basis for CMOS cellular biosensors. Next, we introduce a CMOS frequency- shift magnetic sensor scheme which performs detections without post-processing or external biasing magnetic field. Finally, we will demonstrate a CMOS magnetic cell based sensor which achieves real-time chemical detections; such a sensor scheme can be utilized for massively paralleled high- throughput chemical screening in drug development.