Jet impingement and two-phase cooling apparatuses with sloped vapor outlet channels are disclosed. In one embodiment, a cooling apparatus includes a fluid inlet channel, a jet orifice surface having one or more jet orifices fluidly coupled to the fluid inlet channel such that coolant fluid within the fluid inlet channel flows through the one or more jet orifices as one or more impingement jets, and a target surface. The target surface and the jet orifice surface define an impingement chamber where the one or more impingement jets impinge the target surface at an impingement region such that at least some of the coolant fluid changes to a vapor. The cooling apparatus further includes a plurality of sloped vapor outlet channels that are fluidly coupled to the impingement chamber. Coolant fluid flows through the plurality of sloped vapor outlet channels after it impinges the target surface.