Plants shrubs up to 1(1.5) m tall; young stems appressed pubescent. Leaves petiolate; petioles 1-8(-12) mm long; blades lanceolate to ovate, 1.2-7.5 cm long, 0.3-3 cm wide, subglabrous to densely puberulent, bases cuneate to truncate, tips acute to rounded. Spikes 1-7.7(-10) cm long, with many pairs of flowers; peduncles up to 8 mm long; bracts elliptic to ovate, subglabrous to densely puberulous, the lower 8-15 mm long, 2.5-8 mm wide, tips acute to acuminate, pungent. Calyces 3-5 mm long; corollas pale blue to bright blue, tubes 4-8)-10) mm long, lobes 6-13 mm long. Capsules 8-12 mm long; seeds smooth and shiny.
Megalochlamysviolacea grows in bushland or woodland, on rocky slopes in shallow soil over limestone or on alluvial plains at 100-1380 m in regions N1-n3, C2, and S1-3 of the Flora of Somalia and in Djibouti, Eritrea, Ethiopia, Sudan and/or South Sudan, Kenya, Yemen, Oman, and Saudi Arabia.