Dietes bicolor forms clumps of erect sword-shaped leaves. The adult plant is approximately 1m wide and 1m tall. The leaves are 1 to 2 cm wide, light green in colour and have a double central vein. They are arranged in flat fans similar to other members of the iris family. The plant spreads by means of its modified stems (rhizomes), which are located below the soil surface.
The flowers are about 60 mm in diameter, flat, light yellow with brown markings and are produced on the ends of much-branched flower stalks.