Method and apparatus are disclosed for mobile device tethering for a remote parking assist system of a vehicle. An example vehicle includes first and second wireless modules and a processor. The processor estimates a region of probability representative of possible locations of a mobile device based on a first signal strength indicator. When the region of probability overlaps a virtual boundary, the processor polls a key fob, estimates a distance of the key fob from the vehicle based on a second signal strength indicator, and when the key fob is within the virtual boundary, enable autonomous parking.