A new and distinct cultivar of river birch tree, Betula nigra, named 'WHIT XXV,' characterized as having a tree form that is broadly pyramidal to oval and may be grown with a single stem or multiple stems for greater landscape appeal. The bark of the 'WHIT XXV' is creamy-white during the late summer, fall and winter, developing its coloration at a young age when most stems are about 0.75 to 1.0 inch in diameter. The leaves are dark green of moderate size and turn yellow-gold in the fall.