This species is characterized by its glabrous leaves, stems, and inflorescences, medium-sized elliptic leaves, spiciform inflorescences with perhaps half a dozen sessile flowers, small truncate involucels, truncate calyx limbs 4.5-5.5 mm long, and white corollas with tubs 7-9 mm long and the lobes about as long as the tubes. The leaves are coriaceous with shortly acute apices and revolute margins (on dried specimens). The calyx limbs are glabrous.

Retiniphyllum guianense is similar to Retiniphyllum truncatum, which is much more widely distributed and has strigose calyx limbs 2-4 mm long. Retiniphyllum guianense is also similar to Retiniphyllum schomburgkii, with pubescent leaves, stems, and inflorescences.