Technologies for secure hybrid standby power management include a computing device with a processor supporting low-power idle standby. An operating system writes a power management sleep request, such as an ACPI S3 request, to a power management control register of the computing device. The processor traps the write to the power management control register and executes a firmware sleep mapper that causes the processor to enter an idle standby power state such as S0ix. The firmware sleep mapper may be included in a firmware isolated memory region. The address of the firmware sleep mapper may be included in a model-specific register of the processor. The processor may verify the firmware sleep mapper before execution. In response to a wake event, the processor resumes the firmware sleep mapper, which switches the processor to real mode and jumps to a waking vector of the operating system. Other embodiments are described and claimed.