The feasibility and development of a field emission based anisotropic vector magnetometer is presented. Within this scope current magnetic sensing technology is investigated and compared. The advantages of, and need for, a field emission based magnetic sensor are then discussed. Background theory, simulation, fabrication, testing, and future developments of field emission magnetometers are presented. The possible applications of field emission to other technologies are also investigated. The magnetic sensing device presented uses a sharp field emitting tip with a radius of the order of 100nm which is fabricated using standard silicon processing techniques on highly n-doped silicon. Under a vacuum level of 10"6 mBar and at room temperature, a potential applied to a surrounding gate electrode extracts from this tip a beam of electrons which is incident upon two separate anode electrodes. In the absence of an external magnetic field the electron current incident on each of these two electrodes is equal, while in the presence of a magnetic field the Lorenz force skews the beam towards one of the electrodes, resulting in a differential current which is proportional to the magnetic field.