In this paper, an analytical solution is developed for active seismic earth pressure on the back of a retaining wall supporting an unsaturated c-ϕ backfill. A retaining wall with vertical back and supporting a horizontal backfill with a planar failure surface has been considered for the analysis. The effects of matric suction, soil friction angle, wall friction angle, horizontal and vertical earthquake acceleration components on the active earth pressure have been explored. The observations of the analysis quantified that the matric suction being additive in nature to the cohesion decreases the earth pressure even further.