Hybrid electric vehicles offer the advantages of reduced emissions and greater travel range in comparison to conventional and electric ground vehicles. Regardless of propulsion strategy, efficient cooling of electric motors remains an open challenge due to the operating cycles and ambient conditions. The on-board thermal management system must remove the generated heat so that the motors and other vehicle components operate within their designed temperature ranges. In this paper, an integrated thermal structure, or “cradle”, efficiently transfers heat within the motor shell to the end plates for transmission to an external thermal bus will be presented. A radial array of heat pipes function as an efficient thermal connector between the motor and heat connector or thermal bus depending on the configuration. Cooling performance has been evaluated for various driving cycles. Numerical results show that 1.3 kW of peak wattage can be accommodated with free convection while 3.2 kW correspond to forced convection using 16.3 W of electric power. Internal motor temperature was maintained within the prescribed level as evident by the 90 °C and 70 °C values, respectively.