This paper reports on the creation of a novel 3D Hall-effect sensor based on an anisotropically etched, inverted pyramid structure. Specific biasing and sensing contact configurations are employed to extract the in-plane or out-of-plane components of the magnetic field, eliminating cross-sensitivity by symmetry. Simulations were performed to verify the functionality and performance of the device, and the results suggested that sensitivity can be manipulated by varying the size-to-contact ratio. MEMS and CMOS processes were leveraged to create small-footprint, single-structure magnetometers with high in-plane/out-of-plane sensitivity. Four different geometries were characterized and maximum in-plane sensitivities of 80.1 V/A/T and 22.3 mV/V/T and in-plane to out-of-plane sensitivity ratios of up to 0.77/1.09 (current/voltage-related) were measured. The presented pyramid structure enables a path toward CMOS-integrated, spatially isotropic magnetometers using a single Hall sensor.@en