Wahlenbergia thunbergiana grows narrow leaves at nearly right angles to the stems or they recurve quite sharply as in the picture, about parallel to the stem. The leaves are alternate or spiral up the stems, occasionally opposite and bearing no stalks.

The leaf margins are entire, mostly curved up to create a shallow channel on top and the tips pointed. The leaf colour is dark green, the upper surface glossy and darker green than the lower one. Faint, short hairiness is visible on both surfaces as well as the upper stems. The leaves become about 1 cm long (Le Roux, et al, 2005; iNaturalist).