A mobile wireless communications device may include first and second housings coupled together and moveable between first and second positions. The mobile wireless communications device may also include wireless transceiver circuitry carried by at least one of the first and second housings, a magnetic sensor carried by the first housing and coupled to the wireless transceiver circuitry, and a magnet carried by the second housing. The mobile wireless communications device may also include a magnetically conductive body operatively coupled between the magnetic sensor and the magnet when the first and second housings are in the first position.