The propulsion system of a power-split hybrid vehicle typically comprises of an engine drive system in which the engine, drivetrain and generator are mechanically coupled on a planetary gear set driveline while the electric drive system consists of a high voltage battery and a traction motor. Traditionally, Hardware-in-the-Loop (HIL) simulations of hybrid vehicle controls and high-voltage battery controls have been implemented on separate HIL benches which were exclusively targeted to hybrid vehicle controls and battery controls simulations respectively. This research demonstrates an implementation of enhanced fidelity of a power-split hybrid vehicle powertrain controls HIL by integrating it with high- voltage traction battery subsystem HIL by networking the two aforementioned HIL systems together. The power-split hybrid vehicle HIL typically used simplified battery plant and controller models, and therefore, the addition of the high- voltage battery HIL provided a more detailed simulation of the high-voltage battery in which each cell is modeled such that cell voltage varies based on initial SOC and temperature, capacity, fan speed, self-discharge, and other chemistry-based parameters. The integration of the battery HIL also provides the high-voltage interface to the battery controller hardware and incorporates actuators such as the electrical fan and high-voltage contactors into the loop. The development of this networked HIL setup required the development of a multi-processor plant model that would execute synchronously on both HILs and the integration of the processors of both HILs. The 2017 Ford Fusion Hybrid was used as the platform for this research. The power-split hybrid vehicle HIL simulation included the powertrain controllers and actuators while a Simulink representation was used for the simulation of the other subsystem plants and controllers. The high-voltage battery HIL simulation included the battery controller and actuators. For both HIL benches, dSPACE HIL simulators provided the real-time interface between the hardware and the model simulations. The battery subsystem performance of the vehicle was used as the baseline for comparison between the battery subsystem performances of the simplified power-split hybrid vehicle HIL and the networked HIL setup to understand the increased fidelity and accuracy of the latter.