A processor memory mapped boot system includes a processing system having a processor memory subsystem, and a memory system having at least one memory device. A Basic Input/Output System (BIOS) engine is coupled to the processing system and the memory system, and is configured to begin boot operations and detect a boot memory mode setting for the processor memory subsystem. The BIOS engine configures a memory space that includes the at least one memory device and the processor memory subsystem. In response to detecting the boot memory mode setting, the BIOS engine will configured the processor memory subsystem to provide a first memory region of the memory space. The BIOS engine will then complete boot operations utilizing the processor memory subsystem providing the first memory region of the memory space.