Blastobasis chuka is a moth in the family Blastobasidae. It is found in Kenya, where it is known from the south-eastern coast and the central highlands. The length of the forewings is 6.3–8.2 mm. The submedian fascia are faint. The basal one-third, from the base to the submedian fascia are pale brown intermixed with a few brown scales, the distal two-thirds from the submedian fascia to the margin are brown intermixed with a few pale brown scales. The hindwings are pale grey.