Callitris muelleri is a small tree or shrub growing to 6 meters tall. The leaves are hairless, glaucous to green in colour, with mature leaves measuring 5-10 millimeters long, juvenile leaves longer. This species is monoecious. The male cones measure 3 millimeters long and occur in clusters at the ends of the leaves, while the female cones are spherical, measure 20-30 millimeters in diameter, occur solitarily or in clusters, and may remain on the branches after maturity.^[3]