The simple, about sessile leaves of Agathosma roodebergensis spiral and ascend around the stems. They are ovate with pointed tips tending to curve up slightly. The leaves are finely hairy. The leaf dimensions are about 4 mm long and 3 mm wide. They exude a sweet fragrance, more when crushed.
The flowers are densely clustered low on upper branchlets below the leaves. The calyces in picture are dull maroon with dark, rounded sepal lobe tips. Some plants have greenish calyces and creamy pedicels.
The flowers have white, spreading petals, oblong to oblanceolate and round-tipped. The long stamens are exserted and diverging in the usual Agathosma manner.
The flowers are seen from late autumn to spring.
The fruits are three-chambered (Vlok and Schutte-Vlok, 2015; Bond and Goldblatt, 1984; iNaturalist).