Rubroboletus pulcherrimus is found in western North America, from New Mexico and California to Washington, and may feasibly occur in British Columbia, Canada. One source notes it grows at low altitudes in the Cascade Range and Olympic Mountains; another claims it grows at high elevations, over . Fruiting in autumn, it grows singly or in groups (although another source claims never in groups) in humus in mixed woodlands. In the original publication describing the species, Thiers and Halling note that it is associated with forests containing tanbark oaks (Lithocarpus densiflora), Douglas fir (Pseudotsuga menziesii), and Grand Fir (Abies grandis). Smith and Weber mention increased fruitings after warm heavy fall rains following a humid summer.