This paper presents a novel hybrid CMOS/MEMS tilt sensor with a 5∘ resolution over a 300∘ range. The device uses a MEMS-based semicircular mass suspended from a rigid body, projecting a shadow onto the CMOS-based optical sensor surface. A one-dimensional photodiode array arranged as a uniformly segmented ring is then used to determine the tilt angle by detecting the position of the semicircular mass. The complete sensor occupies an area of under 2.5 mm × 2.5 mm.