The Rocky Mountain Juniper Tree is small with a wide, irregular crown with a wildly twisted trunk reaching 13 m in height. The needles are flat and twisted, in pairs and barely overlapping but covering the twig in 4 rows, but on young, faster-growing branches the leaves may be longer and more needle-like. They are pale yellowish to green, turning to grayish-green on older branches. The cones are rounded, small and located at the ends of the branches and are a bright to dark blue color with a grayish tinge.
The bark is divided into narrow flat ridges that are broken into thin strips that are reddish to grayish brown. It grows best in dry rocky or sandy soils, especially along lake and stream shores with dry, rocky, south-facing bluffs. It can be found throughout southern British Columbia and in a few places on southern Vancouver Island.
Rocky Mountain Juniper Tree often grows in pure open groups of trees, but it can occur mixed with douglas fir on Vancouver Island.