In order for electronics packaging power density to increase, innovations and improvements in heat transfer are required. Electrification of transportation has the potential for significant fuel and energy savings. Changing to an electrified drive train requires reliable and efficient power electronics to provide power conversion between alternating current motors and direct current energy storage. For high power transportation systems like aircrafts or heavy vehicles, the power density of power electronics needs to be improved. Power density is also an enabler for high power military devices that must be used and transported via air, ground, and sea. This paper summarizes the outcome of a collaborative and multidisciplinary research effort aimed at co-designing a novel electronics cooling device that utilizes two-phase fluid flow. Two-phase flow cooling has been known for decades as well as the risks associated with it: critical heat flux (CHF), dry-out, and thermal runaway. Our research de-risks the two-phase cooling technology by swirling the flow to remove the bubbles from the wall and confining them at the core of the cooler. The combined effects of gas phase removal, enhanced nucleation, and dramatic liquid film agitation and rupture have been quantified by our experiments: double the heat transfer coefficient with only 13% increase in pressure drop. Besides advanced fluid-dynamics, our Package-Integrated Cyclone Cooler (PICCO) utilizes cutting edge packaging and additive manufacturing technology such as direct deposition of a metal substrate and circuits (dies) on a complex helical cooler that can only be manufactured via three-dimensional printing. By co-designing and testing the cooler, we have quantified the impact of the swirled flow on the junction temperature with respect to a conventional (non-swirl) two-phase-flow-cooled power electronics package. At steady-state, our post-test thermal simulations predict a junction temperature reduction from 185 °C to 75 °C at the same power dissipation. When the heat load is unsteady (United States Environmental Protection Agency Urban Drive Cycle), the junction temperature reduction is 140 °C to 60 °C.