An intelligent work vehicle preheating system includes an electric drive subsystem containing a battery pack, a hydraulic subsystem containing a first hydraulic fluid (HF) heating device, and a first HF temperature sensor. A memory stores a first minimum target temperature at or above which a first hydraulic fluid body contained in the hydraulic subsystem is desirably maintained. A controller architecture selectively places the intelligent work vehicle preheating system in an off-duty preheat mode when the electric drive subsystem is connected to an external power supply utilized to charge the battery pack. The controller architecture further controls the HF heating device to heat the first hydraulic fluid body when (i) the intelligent work vehicle preheating system is placed in the off-duty preheat mode, and (ii) the current temperature of the first hydraulic fluid body is less than the first minimum target temperature.