Euphorbia eleanoriae is a small shrub that grows to a height of 20–40 cm. The stems are glabrous and densely branched, with erect-ascending, brittle branches. The basal stems have dark gray, longitudinally fissured bark, while the leafy branches are longitudinally furrowed, green or red-tinted, and 0.6–1 mm in diameter, with internodes 6–30 mm long. The leaves are simple, opposite, and decussate, sometimes spirally arranged, with elliptic to broadly ovate blades measuring 10–20 mm long and 6–14 mm wide. The leaf apex is rounded or retuse, often mucronulate, and the base is subcordate, less commonly truncate or rounded. The surfaces are glabrous, drying dull and pale green, slightly discolorous, with faint white punctuations on the upper surface and a grayish green lower surface. The margins are entire and usually slightly involute, with 5–7 pairs of lateral veins, 3–4 pairs arising subpalmately from the base, and obscure venation. The petioles are short, 0.5–1.5 mm long, and glabrous, and the stipules are broadly triangular or obtuse, 0.5–1 mm long, glabrous externally, and villous internally. The flowers are solitary and terminal at branch tips, in cyathia with 1–1.5 mm long, glabrous peduncles. The involucre is campanulate, 2–3 mm long, 2–2.5 mm in diameter, densely villous internally, glabrous externally, green or dark purple. The glands are 4–5 in number, glabrous, and purple, each with a broadly obovate to subcircular white petaloid appendage 0.7–1.5 mm long and 1.5–2.6 mm wide, with entire or irregularly sinuate or lacerate margins. The flowers are unisexual and highly reduced. The pistillate flowers are solitary on a gynophore, while the staminate flowers are in groups of 5 cymules, each with 1 to several flowers. The male flower is reduced to a single stamen with an articulation at the junction of the pedicel and filament, subtended by slender bracteoles. The stamens are 0.6–0.7 mm long, with dark purple bilobed anthers. The ovary is superior, initially erect, glabrous, or rarely tomentellous, with dark purple and thickened bifid styles. The fruit is a 3-angled capsule 2.5–2.8 mm long and 2.3–3 mm in diameter. It is broadly ovoid, glabrous, green with purple-red margins and apex, recurved on a glabrous gynophore up to 2 mm long. The seeds are 1.8–2.0 mm long and 1.0–1.2 mm in diameter, with a brownish-white smooth seed coat. It is found on north-facing, steep, narrow ridge crests and outcrops and in small populations within relictual native lowland or montane diverse mesic forests and shrublands at elevations ranging from 270-1,100 meters.