The long-tubed, two-lipped flowers of Streptocarpus dunnii grow in a many-flowered, often dense panicle of branched racemes. The calyx of each flower is small, its five sepals narrow.
The corolla is narrowly trumpet-shaped ending in five short, rounded, spreading lobes. These lobes are coral-red to brick-red or orange-red around the mouth, the tube inside whitish to creamy yellow. Vertical rows of dark red dots are present up the corolla tube to the mouth. This slightly curved tube is about 3 cm to 4 cm long with short gland-tipped hairs on its outside surface.
The two lemon-yellow, arched filaments of the stamens bring the anthers together in the flower mouth. With them is the pale purplish style from the superior, one-locular ovary. Both these male and female parts of the bisexual flower curve in the flower mouth; are not exserted.
Flowering happens from late spring to summer. The fruit capsule is spirally twisted in the general Streptocarpus way (Manning, 2009; Onderstall, 1984; Germishuizen and Fabian, 1982; iNaturalist).