An electronic device may include a circuit board, an IC carried by the circuit board, and an RF shield above the IC. The circuit board may include a dielectric layer, and a thermally conductive body in the dielectric layer. The thermally conductive body may have a first heat transfer surface coupled to the IC. The thermally conductive body may extend laterally within the dielectric layer and outward past the RF shield and defining a second heat transfer surface. The electronic device may include a heat sink coupled to the second heat transfer surface.