Phyllonorycter brachylaenae is a moth of the family Gracillariidae. It is known from South Africa.[1] The habitat consists of understory vegetation in secondary forests.
The length of the forewings is 3.06–3.33 mm. Adults are on wing from early March to mid-May and from late June to late October.[2]
The larvae feed on Brachylaena discolor and Brachylaena rotundata. They mine the leaves of their host plant.