Grewia bicolor is a multi-stemmed shrub or small tree, up to 9 m high. Its bark is smooth, grey, becoming dark grey and deeply fissured and peeling away in straps with age. The young branchlets are velvety grey or brown.

The leaves are alternate, simple and elliptic to slightly ovate, 15-80 x 10-32 mm, with a broadly tapering to rounded apex. They are 3-veined from the asymmetrically lobed base, rounded to slightly cordate, held horizontally or drooping, glossy green above, almost white and silvery hairy below, while the margins are entire to slightly serrated. The petiole (leaf stalk) is about 1-8 mm long.

The flowers are small, bright yellow, borne in axillary clusters at the end of branches. They are often borne in profusion, with sepals up to 12 mm long and petals shorter. The flowering time is October-March.

The fruits are round and fleshy drupes (fruits such as plums), reddish brown or orange and black when ripe, entire or deeply 2-lobed, up to 6 mm in diameter.