The flower of Jamesbrittenia pristisepala has the long tube with characteristic kink typical of the genus, some distance back from the spreading corolla lobes. In this species the kink may be a further back from the corolla mouth than in several other members of the genus.
The petals are bright to pale purple or nearly white, dark at the mouth around the yellow colouring found inside the throat of the corolla. The petals are oblong and two-lobed or rounded at their tips.