Rankine classic earth pressure solution has been expanded to predict the seismic active earth pressure behind rigid walls supporting c–φ backfill considering both wall inclination and backfill slope. The proposed formulation is based on Rankine's conjugate stress concept, without employing any additional assumptions. The developed expressions can be used for the static and pseudo-static seismic analyses of c–φ backfill. The results based on the proposed formulations are found to be identical to those computed with the Mononobe–Okabe method for cohesionless soils, provided the same wall friction angle is employed. For c–φ soils, the formulation yields comparable results to available solutions for cases where a comparison is feasible. Design charts are presented for calculating the net active horizontal thrust behind a rigid wall for a variety of horizontal pseudo-static accelerations, values of cohesion, soil internal friction angles, wall inclinations, and backfill slope combinations. The effects of the vertical pseudo-static acceleration on the active earth pressure and the depth of tension cracks have also been explored. In addition, examples are provided to illustrate the application of the proposed method.