An electro-hydraulic brake assembly comprises a hydraulic control unit (HCU) body having a top surface and a bottom surface opposite the top surface and defining a master cylinder bore and a pressure supply bore. A fluid reservoir is disposed on the top surface. A primary piston is slidably disposed in the master cylinder bore and configured to supply brake fluid to a wheel brake in response to pressing of a brake pedal. A pressure supply unit includes: a pressure supply piston disposed within the pressure supply bore; a motor located on the bottom surface of the HCU body and having a motor shaft. An actuator mechanism includes a threaded shaft configured to be rotated by the motor shaft, and a nut coupled to the pressure supply piston, together causing the pressure supply piston to translate linearly through the pressure supply bore in response to rotation of the motor shaft.